VISION WORLD: ABOUT SQL SERVER

SQL SERVER

SQL Server is a Database Management System (DBMS) created by Microsoft. In early days, File Management System is used for storing data permanently on secondary storage device and retrieves it back whenever necessary. But because of some drawbacks in file management system, a new data management system was developed, called as DBMS.

File Management System

In File Management System, data is organized in the form of Fields, Records and Files. A field is meaningful collection of characters, a record is collection of related fields and a file is collection of similar type of records. As an example you can observe the following table that contains student details.

Fields

Records

File

Sno	Sname	Course
1	SAI	C
2	KRISHNA	CPP
3	RAHUL	ORACLE
4	SARMA	DOT NET
5	PARDHU	JAVA

Drawbacks Of File Management System

The drawbacks of file management system that leads to the development of DBMS are as follows.

Data Redundancy and Inconsistency : In file management system data is duplicated, which is called as redundancy. Because of this duplication memory is wasted and it is inconsistent for the user if he/she has to make changes to the duplicated data. This is because changing the data at one place will not reflect in all places where it is duplicated and user has to make the change at every place where it is duplicated.
Atomicity Problem : “Either all the changes in a transaction must occur nor neither occur”. This rule is called atomicity rule and this rule is violated by the file management system, which is called as atomicity problem. For example, if the transaction is to transefer1000/- from Account A to Account B, the two steps in the transaction will be as follows.

Deduct 1000/- from Account A
Add 1000/- to Account B

If there is a system failure or power failure after deducting amount from Account A and before adding this amount to Account B, then amount is deducted from account A but is not added to account B, which violates atomicity rule. According to atomicity rule, If second step is cancelled then first step must also be cancelled other wise second step must also be performed.

Concurrent Access Anomolies : The problems that occur when more than one user try to access the same data in the same file are called as concurrent access anomalies. For example within a bank there is a joint Account A, whose balance amount is 5000/-. Two customers of the joint account are withdrawing amount from the Account A, at the same time from two different branches of the bank. One is withdrawing 500/- and another is withdrawing 1000/-. As both are withdrawing at the same time, balance amount is read as 5000 by both the computers. First computer will deduct 500/- and makes the remaining balance as 4500/-. Second computer will deduct 1000/- and will make the remaining balance as 4000/-. During the process of update only one can update data at a time. Hence finally balance will be shown either as 4500 or 4000 instead of the actual amount 3500/-.
Security Problem : within file management system, if user got the write permission, he can insert new data, update existing data and he can also delete data from the file and it is not possible to restrict the user from updating or deleting data while allowing to insert new data.

Database Management System (DBMS)

DBMS is based on databases. A database is defined as collection of inter-related data. DBMS is defined as collection of databases and a set of programs to work with databases. SQL Server is called as DBMS as it contains databases and a set of programs to work with databases. DBMS overcomes all the drawbacks of file management system. After inventing DBMS, several models are proposed stating various ways of representing data within the database and their advantages, called as data models. These data models are classified into three categories based on their purpose as follows.

Physical Data Models
Conceptual Data Models
Logical Data Models

Physical Data Models : The data models that concentrate on how the data is physically stored within the database are called as physical data models.

Conceptual Data Models : The data models that concentrate on how the data and relationship between data can be represented diagrammatically are called as conceptual data models. One of the most popular conceptual model is Entity-Relationship Model(E-R Model).

E-R model uses the terminology Entity, Attribute and Relationship. An entity is a real world object stored within the database. If you store student information in the database, then student is called an entity, if you store employee information within the database, then employee is called an entity and so on. An attribute is a characteristic feature of the entity. For student entity sid, sname, course, address all these are called as attributes. A relationship is an association between entities. Relationship between entities are classified into one to one(1:1), one to many(1:M) and many to many(M:N).

Within E-R diagrams an entity is represented with a rectangle, an attribute with oval shape and relationship with diamond shape. The E-R diagram for the entities Student and Course is as follows. The relationship type between course and student is one to many. This is because one student can join only one course and a course can be chosen by any number of students.

Student

Course

SID

Sname

Course

CID

Cname

Duration

Joins

M 1

Logical Data Models : The data models that concentrate on what data is stored in the database and what type of relationship exist between data are called as logical data models. The following lists of logical data models are available.

1. Hierarchical Data Model

2. Network Data Model

3. Relational Data Model

4. Object Data Model

5. Object Relational Data Model

Hierarchical Data Model : in this data model data is organized hierarchically like in tree data structure. Within hierarchical database model it is not possible to represent many to many relationships. This drawback leads to the development of network data model. Student information can be represented in hierarchical data model as follows.

College

CID 1001

CID 1002

CID 1003

SID 10001

SID 10002

SID 10010

SID 10011

Courses

Students

Network Data Model : in this data model also data is represented same as in case of hierarchical data model except that it can represent many to many relationship. Student information is represented in network data model as follows.

College

CID 1001

CID 1002

CID 1003

SID 10001

SID 10002

SID 10010

SID 10011

Courses

Students

With

Many To Many RelationShip With Course

In both hierarchical and network data models, organization of data is very difficult as it is organized like a tree data structure. Especially deleting a record will be very complex process as all records that are based on deleted record must be rearranged. These drawbacks lead to the development of relational data model.

Relational Data Model : Relational data model was proposed by E.F.Codd in 1970. He proposed the model theoretically and first practical implementation of relational model was System-R and is developed by IBM Corporation. In relational data model data is organized in the form of attributes, tuples and relations. Attribute, tuple and relation can be compared to a field, record and file in file management system. These are technical terms given by E.F. Codd and now a days these terms are replaced with column, row and table respectively.

Attributes or

Columns

Tuples or Rows

Relation or Table

Sno	Sname	Course
1	SAI	C
2	KRISHNA	CPP
3	RAHUL	ORACLE
4	SARMA	DOT NET
5	PARDHU	JAVA

As organization of data in relational data model is similar to file management system, it is very easy to maintain when compared to hierarchical and network data models. Now a days most of the DBMS are RDBMS. Examples are SQL Server, Oracle,DB2, MS Access etc.,

Object Data Model : This data model is based on object oriented concepts of programming. This model provides OOP features within the database. This model also becomes popular as it has advantages of OOP. Examples are Object Store, Cactus etc.,

Object Relational Data Model : this model combines the features of object data model with the features of relational data model. Hence this model has both the advantages of relational data model as well as object data model. Example is Oracle 8.0 onwards.

Relational Data Model

Relational data model is proposed by E.F.Codd in 1970. First practical implementation of relational model is System-R developed by IBM Corporation. Later several DBMS are developed based on relational model and are called as relational database management system (RDBMS). SQL Server developed by Microsoft Corporation, Oracle developed by Oracle Corporation and DB2 developed by IBM Corporation are some examples of RDBMS.

In relational data model data is organized in the form of attributes, tuples and relations. The attribute, tuple and relation can be compared to a field, record and file in file management system. These are technical terms given by E.F. Codd and now a days these terms are replaced with column, row and table respectively.

Attributes or

Columns

Tuples or Rows

Relation or Table

Sno

Sname

Course

SAI

KRISHNA

CPP

NULL

RAHUL

ORACLE

SARMA

DOT NET

PARDHU

JAVA

Relational data model provides various constraints to maintain data integrity within the database. These constraints are called as integrity constraints. Integrity constraints supported by Relational data model are as follows.

1. Not Null : if we insert a row into a table without providing value for a column, then the value in that column is called NULL value. In the above student table third row is inserted without giving a value for sno column. Hence this row contains NULL for sno column. If you want to restrict the user from inserting a NULL value in to a column, then you can specify Not Null constraint on that column.

2. Unique : when you don’t want to allow duplicate values in to a column, then you can specify unique constraint on that column. For example, if you take student table, sno must be unique i.e. sno given for one student must not be given to another student. To implement this condition on sno column, you have to specify unique constraint on sno column.

3. Primary Key : when you specify primary key constraint on a column, then null values as well as duplicate values are not allowed into that column. A table must contain an attribute as primary key attribute to identify each row of the table uniquely.

i) Candidate Key : An attribute of the table that will uniquely identify every tuple of the table is called as candidate key. A table can contain more than one candidate key. Among all available candidate keys, the candidate key used by the user to identify the tuples uniquely is called as primary key. For example, if we take the Department table that contains Deptno, Dname and Location Columns, both Deptno and Dname Columns are candidate keys. But as we use Deptno to uniquely identify the rows of department table, Deptno is called as primary key.

ii) Secondary Key : An attribute that is used to uniquely identify the rows of the table when primary key fails is called as secondary key. For example, when we have to retrieve marks of a student, we will provide student’s hall ticket no. Here hall ticket no is primary key. If user lost his hall ticket no., then we can use student name and his father name combination to retrieve marks. Hence combination of these two columns is called as secondary key.

4. Foreign Key : this constraint is used to create relationship between two tables. When you specify foreign key constraint on a column, you must specify a primary key column as reference to it. As a foreign key refers to a primary key, it is also called as referential integrity constraint. A foreign key constraint will restrict the user from inserting a value that doesn’t exist in the referenced primary key column.

Normalization

The process of minimizing data redundancy through a series of steps called normal forms is called as normalization. Total normalization process includes 8 normal forms.

First Normal Form (1NF)
Second Normal Form (2NF)
Third Normal Form (3NF)
Boyce-Codd Normal Form (BCNF)
Fourth Normal Form (4NF)
Fifth Normal Form (5NF)
Domain/Key Normal Form(DKNF)
Sixth Normal Form(6NF)

First Normal Form (1NF) : A relation is said to be in first normal form if and only if a primary key is defined for the relation and all non-key attributes are dependent on key attributes. The attributes that are part of primary key are called as key attributes and all remaining attributes are called as non-key attributes. As an example observe the following relation that contains information regarding various projects and employees working in those projects.

PID	Proj. Name	EmpID	Ename	Job	Charge/Hour	Hours Worked
P101	College Maintenance	1001	A	Sr. Programmer	500	3
P101	College Maintenance	1007	K	DBA	750	2
P101	College Maintenance	1003	M	Jr. Programmer	300	5
P102	Hospital Maintenance	1001	A	Sr. Programmer	500	5
P102	Hospital Maintenance	1005	S	DBA	750	3
P102	Hospital Maintenance	1003	M	Jr. Programmer	300	5
P102	Hospital Maintenance	1009	R	Jr. Programmer	300	4

In order to convert the above table to 1NF, a primary key must be defined for the table and all non-key attributes must be dependent on key attributes. In this table, it is not possible to define primary key on a single column as every column can contain duplicate values. Hence we can define primary key on the combination of PID and EMPID Columns. Now by giving the values of PID and EMPID columns, we can retrieve the values of every other column in the table. Hence the table is said to be in 1NF. Finally Table is represented as follows after defining a primary key on PID and EMPID columns.

(PID,EMPID) Pname, Ename, Job, Charge/Hour, Hours Worked

Second Normal Form (2NF) : A relation is said to be in 2NF if and only if the relation is in first normal form and no partial dependencies exist in the relation. If primary key is defined on more than one attribute and a non-key attribute is completely dependent on only one key attribute then that dependency is called as partial dependency. The above table after conversion to 1NF, contains PID and EMPID combination as primary key. But to get PNAME there is no need to provide EMPID. Hence PNAME is partially dependent on key attributes. In the same way to get ENAME, JOB, CHARGE/HOUR and HOURS WORKED, there is no need to provide PID. Hence these attributes are also partially dependent on key attributes. The above relation is not in 2NF.

To convert the above relation to 2NF, we have to divide the table as follows.

1. (PID) Pname

2. (EMPID) Ename, Job, Charge/Hour

3. (PID,EMPID) Hours Worked

Now all three relations are said to be in 2NF, as they doesn’t contain partial dependencies.

Third Normal Form (3NF) : A relation is said to be in 3NF, if and only if the relation is in 2NF and no transient dependencies exist in the relation. If a non-key attribute depends on another non-key attribute, then that dependency is called as transient dependency. In the above three tables that obtained by converting the table of 1NF to 2NF, second table contains CHARGE/HOUR column, which was actually dependent on JOB but not on EMPID. To convert this table, which was not in 3NF to 3NF, we have to divide the table as follows.

1. (PID) Pname

2. (EMPID) Ename, Job

3. (JOB) Charge/Hour

3. (PID,EMPID) Hours Worked

Now all the four tables are in 3NF, as they don’t contain transient dependencies.

As the normalization steps proceed to higher normal forms, no. of tables in the database will increase. When no. of tables increases, the database performance will be reduced as we have to combine the data from more than one table. This is the reason why database designers are restricted to 3NF.

De-normalization : Converting the tables from their current normal form to their previous normal form is called as de-normalization.

INTRODUCTION TO SQL SERVER

SQL Server is a client-server Relational Database Management System developed by Microsoft Corporation. A client-server RDBMS is an RDBMS that can be shared. SQL Server is the RDBMS chosen as back end by most of the developers on Windows operating system. This is because

It is tightly integrated with Windows
It is easy to use as it provides wizards to perform various tasks like object creation, database tuning, backup etc.,
It scales from mobile laptop to symmetric multi-processor systems.
It provides business intelligence concepts, which are until now available only in oracle and other expensive DBMS’s.
It is a bundle of at least four products Relational Database Engine, Analysis Services, Reporting Services and Integration Services. Relational Database Engine is used to work with database and database objects, analysis service is used to work with business intelligence concepts like data warehousing and data mining. Reporting Services is used to create and deploy enterprise reports and Integration Services is used to integrate data from different types of data sources to SQL Server.

History Of SQL Server

SQL Server was developed and implemented by Sybase Corporation. In 1988, Microsoft licensed SQL Server for OS/2 operating system and began developing it for windows in early 1990. At almost the same time, further development of SQL Server for OS/2 has been cancelled. In 1994, Microsoft cancels the agreement with Sybase and starts developing SQL Server for windows. Since then several versions of SQL Server are released and the new version in the market is SQL Server 2005.

New Features in SQL Server 2005

SQL Server 2000 provides Enterprise Manager to work with wizards and Query Analyzer to work with SQL queries. In SQL Server 2005, these two programs are combined into a single program called Management Studio.
In today's connected world, data and the systems that manage that data must always be secure yet available to your users. With SQL Server 2005, users and information technology (IT) professionals across your organization will benefit from reduced application downtime, increased scalability and performance, and tight yet flexible security controls.
SQL Server 2005 includes key enhancements to enterprise data management in Manageability, Availability, Scalability and Security areas.
SQL Server 2005 makes it simpler and easier to deploy, manage, and optimize enterprise data and analytical applications.
SQL Server 2005 simplifies management by providing one integrated management console to monitor and manage the SQL Server relational database, as well as Integration Services, Analysis Services, Reporting Services, Notification Services, and SQL Server Mobile Edition across large numbers of distributed servers and databases.
Investments in high-availability technologies, additional backup and restore capabilities, and replication enhancements will enable enterprises to build and deploy highly available applications. Innovative high-availability features such as database mirroring; failover clustering, database snapshots, and enhanced online operations will minimize downtime and help to ensure that critical enterprise systems remain accessible.
Database mirroring allows continuous streaming of the transaction log from a source server to a single destination server. In the event of a failure of the primary system, applications can immediately reconnect to the database on the secondary server. The secondary instance detects failure of the primary server within seconds and accepts database connections immediately.
SQL Server 2005 introduces a dedicated administrator connection to access a running server even if the server is not responding or is otherwise unavailable. This allows you to execute diagnostic functions or Transact-SQL statements so you can troubleshoot problems on a server. The connection is activated by members of the sysadmin fixed server role and is only available through the SQLCMD command prompt tool either locally or from a remote computer.
Scalability advancements such as table partitioning, snapshot isolation, and 64-bit support will enable you to build and deploy your most demanding applications using SQL Server 2005. The partitioning of large tables and indexes significantly enhances query performance against very large databases.
SQL Server 2005 makes significant enhancements to the security model of the database platform, with the intention of providing more precise and flexible control to enable tighter security of the data.

Management Studio

To work with SQL server 2005 databases and database objects, we have to use management studio. Management Studio provides the following windows.

Registered Servers : this window displays all registered SQL Server servers on the current system. By using this window, you can also register a new SQ Server. To register a new SQL Server, right click on registered servers, then choose “register new server”, and then provide information required to register a server. Short cut to open registered servers window is Ctrl + Alt + G

Object Explorer : this window will display all the databases, database objects, users and logins available in the selected server within registered servers window as a hierarchy. Whenever you want to work with wizards provided by management studio, you can use object explorer. Short cut to open object explorer window is F8

Summary : this window will display all the objects available within the selected category in object explorer. You can work with the objects within summary window by double clicking on them or by right clicking on them and then choosing the corresponding option. Short cut to open summary window is F7

Query Editor : this window is used to write SQL queries and execute them. Whenever you want to work with SQL Server using SQL commands, you can use query editor. Type the query within query editor and to execute it, use the shortcut F5. When there are multiple statements within query editor and you want to execute only one then select the statement you want to execute and then press F5. To open query editor click on New Query button in the toolbar.

Connecting To Server

Whenever you open management studio immediately “connect to server” dialog box will displayed where you have to provide the following information to connect to a database server in the network

Server Type : used to specify what type of server you want to connect to within SQL server. Various options available are Relational Database Engine, Analysis Services, Reporting Services and Integration Services.

Server Name : used to specify the name of the database server within the network to which you want to connect to. If the database is within the local system, by default the local system name will be given as server name.

Authentication Mode : SQL Server supports two types of authentication modes; Windows Authentication and SQL Server Authentication.

In windows authentication mode, the user name and password you specify to login to windows operating system will be treat as login and password to login to SQL Server as well and in this mode there is no need to provide additional login and password to login to SQL Server. In this mode, SQL Server will not provide additional security for the data.

In SQL Server authentication mode, in addition to user name and password you provide to login to windows, you have to provide login and password to login to SQL Server. In this mode, SQL Server will provide additional security for the data in addition to security provided by windows Operating System.

Login And Password : if the mode is selected as SQL Server authentication mode, then valid login and password must be specified to login to SQL Server.

Whenever you try to register a new server using registered servers window, then also you have to provide the same information to register the server on the client system.

TSQL (Transact SQL)

SQL (Structured Query Language) is the common language for any RDBMS to work with the database. In SQL Server the SQL used to work with SQL Server database is called as TSQL. Actually SQL was developed by IBM corporation for their Relational project System – R as part of it. But later it was developed as a separate language and was given a name SEQUEL (Structured English Query Language). SEQUEL was renamed as SQL and was first commercially released by ORACLE Corporation. Features of SQL are as follows.

SQL is a non-procedural or fourth generation language (4GL).
SQL is not case sensitive
In SQL we can break a single statement into multiple lines without using any continuation character.

Commands of SQL are classified as follows.

Data Definition Language (DDL) : The commands of SQL that are used to create database objects, alter the structure of the database objects and delete database objects from database are collectively called as DDL. Examples include Create, Alter and Drop Commands.
Data Manipulation Language (DML) : The commands of SQL that are used to insert data into the database, modify the data of the database and to delete data from the database are collectively called as DML. Examples include Insert, Update and Delete.
Data Query Language (DQL) : The commands of SQL that are used to retrieve data from the database are collectively called as DQL and example is Select.
Data Control Language (DCL) : The commands of SQL that are used to control the access to data stored in the database are collectively called as DCL and examples include Grant and Revoke.
Transaction Control Language (TCL) : The commands of SQL that are used to control the transactions made against the database are collectively called as TCL and examples include Commit, Rollback and Savepoint.

Database

The primary object to create when you want to work with SQL Server is Database. A single SQL Server can maintain 32,767 databases. Within SQL Server, a database is maintained with the help of operating system files. An SQL Server database uses two types of files, data file and Log file.

Data files have the internal data the engine needs, along with any user defined data you place in the database. The database engine has a default data file, and you may add additional data files for storage or organizational reasons. A primary data file will have the extension .mdf and additional data files will have the extension .ndf.
Log files are used to store any modifications made to data, and is heavily used in the process of committing and rolling back changes in the database. A log file will have the extension .ldf.

Creating A Database

Syntax 1 : Create Database DBName

With this syntax SQL Server will create a database with specified name and will automatically create a data file and a log file for the database with default specifications.

Example : Create Database MyDatabase

Syntax 2 :

Create Database DBName

(Name = Logical Name Of the Data File,

FileName = ‘Physical Path and Name Of the Data File’,

Size = initial memory to be allocated for the Data file,

MaxSize = maximum allowed size for the Data file,

Filegrowth = increment to the memory of the Data file

)

Log on

(Name = Logical Name Of the Log File,

FileName = ‘Physical Path and Name Of the Log File’,

Size = initial memory to be allocated for the Log file,

MaxSize = maximum allowed size for the Log file,

Filegrowth = increment to the memory of the Log file

)

Here on option is used to specify information related to Data File and log on option is used to specify the information related to Log File. Name option specifies the logical name of the file used by the SQL Server, FileName option is used specify the physical path and name of the file, Size option is used specify the initial memory to be allocated to the file. By default SQL Server will take it in MB and to change it you can explicitly specify KB or any other measurement of memory. MaxSize option specifies the maximum allowed size for the file. It can be specified as unlimited to not to restrict the file growth. FileGrowth option is used to specify how much increment to be done the file whenever allocated memory is completely utilized by the file.

Example :

Create Database MyDatabase

(Name = MyDatabase_Dat,

FileName = ‘D:\MyDatabase.Mdf’,

Size = 5,

MaxSize = 100,

FileGrowth = 5

)

Log on

(Name = MyDatabase_log,

FileName = ‘D:\MyDatabase.Ldf’,

Size = 5,

MaxSize = 20,

FileGrowth = 1

)

Syntax 3 : Create Database DBName as snapshot of Existing DBName

This syntax is used to create a copy of an existing database as a new database and this option is available only in SQL Server professional edition and is not available in Standard edition.

Altering The Structure Of The Database

After creating the database you may have to create additional data files or log files to the database or delete a data file or log file or make modifications to file specification etc., for this purpose SQL server provides Alter Database command that has the following syntaxes.

1. Alter Database DBName Add File (Data File Specification)

This syntax is used to add an additional data file to an existing database.

2. Alter Database DBName Add Log File (Log File Specification)

This syntax is used to add an additional log file to an existing database.

3. Alter Database DBName Remove File Logical Name Of The File

This syntax is used to delete a data file or log file from an existing database.

4. Alter Database DBName Modify Name = NewDBName

This syntax is used to change the name of the database i.e. renaming the database.

5. Alter Database DBName Modify File (Name = LogicalName , Size=n , MaxSize=n , FileGrowth = n)

This syntax is used to change the file specification for an existing file of the database.

Note : To get the information about an existing database use the system procedure “SP_HELPDB”. This will display information about the data files and log files created for the database along with database information. Syntax will be as follows.

SP_HELPDB ‘DBNAme’

Deleting A Database

To delete a database from SQL server use Drop Database command. Syntax is as follows.

Drop Database DBName

Tables Or Relations

Whenever you want to store data into the SQL server database, first you have to create a table within the database and to create a table you have to specify columns required for the table along with the type of data you want to store in the table and constraints you want to check during the insertion or updating of the data in the table.

Data Types In SQL Server

Category	Data Type	Bytes	Range
Integer	Tiny int	1	0 To 255
	Small int	2	-32768 To 32767
	Int	4	-2147483648 To 2147483647
	Big int	8	-2⁶³ To 2⁶³ – 1
Float	Decimal(P,S) Numeric(P,S)	5 to 17 1-9 5 bytes 10-19 9 bytes 20-28 13 bytes 29-38 17 bytes	Decimal(7,2) will allow a total of 7 digits where 2 digits will be after the decimal point. (ex : 12345.67)
	Float(P) P can be 1-53	If P is 1-24 4 Bytes If P is 25-53 8 Bytes
	Real	4 bytes	Equal to float(24)
	Small Money	4 Byte Decimal
	Money	8 Byte Decimal
Character	Char (n)		Fixed Length Char Data and n can be up to maximum 8000
	Varchar(n)		Variable Length Char Data And n Can be up to maximum 8000
	NChar(n)	a Unicode character will occupy 2 bytes in memory	Fixed Length Unicode char data and n can be up to maximum 4000.
	Nvarchar(n)		Variable Length Unicode char data and n can be up to maximum 4000.
	Text(n)	n can be up to maximum 2GB	Variable length char Data
	Ntext(n)	N can be up to maximum 2³⁰ – 1	Variable length Unicode char data
Binary	Binary(n)	N can be up to maximum 8000	Fixed length binary data
	VarBinary(n)	N can be up to maximum 8000	Variable Length Binary Data
	Image(n)	N can be up to maximum 2³¹ – 1	Variable Length Binary data
	Bit	1	True/False/NULL
Large Value Data Types	Varchar(Max)	2³¹ – 1	Variable Length Char Data
	NVarchar(Max)	2³¹ – 1	Variable Length Unicode Char Data
	VarBinary(Max)	2³¹ – 1	Variable Length Binary Data
DateTime	SmallDatetime	2 2byte integers	Jan 1^st 1900 to june 6^th 2079
	DateTime	2 4byte integers	Jan 1^st 1753 to Dec 31^st 9999
Miscellaneous	SQL_variant	Size varies	Can Store any Type of Data except text, ntext, image and SQL_variant
	Table	Size varies	Can Store a Table
	XML	Size Varies	Can store XML documents
	Timestamp	8 bytes
	Cursor

Constraints In SQL Server

A constraint is a condition given on a column that is checked during insertion and updating data of the table to maintain data integrity within the database. Constraints in SQL Server are classified into Declarative Integrity Constraints and Procedural Integrity Constraints.

Procedural integrity constraints are the constraints that are not possible to specify during the table creation and are specified using triggers. Declarative integrity constraints are the constraints that can be specified during the table creation. Declarative integrity constraints supported by SQL Server are as follows. Declarative integrity constraints can be specified either at column level or table level. A constraint that is specified along with the column definition is called as column level constraint and a constraint that is specified at the end of the table creation is called as table level constraint. In general table level constraints are used when you have to specify the constraint on more than one column. But you can specify a constraint that span on a single column either at column level or table level.

1. Not Null : This constraint is used to restrict the user from inserting null values in to a column. It is not possible to specify the not null constraint at table level.

Syntax : ColumnName DataType Not Null

2. Default : This constraint is used to specify a default value for a column. When user insert a row into the table without providing a value for the column having default value then default value will be inserted in to that column. Default can be specified only at column level.

Syntax : Columnname Datatype [constraint cname] default defautvalue

3. Unique : This constraint is used to restrict the user from inserting duplicate values into a column. When we create a unique constraint on a column then SQL Server will automatically create an index on that column. An index can be clustered or non-clustered. By default SQL Server will create a non-clustered index on unique constraint.

Syntax :

Column Level

ColumnName DataType [Constraint Cname] Unique [Clustered / NonClustered]

Table Level

[Constraint Cname] Unique(Col1,Col2,…,Coln)

4. Primary Key : A column in the table that uniquely identifies every row of the table is called as primary key. To uniquely identify every row of the table, the primary key column must not contain either null values or duplicate values. When we specify primary key constraint on a column, then user will be restricted from inserting null values as well as duplicate values. On primary key column also SQL Server will create an index, which is by default a clustered index.

Syntax :

Column Level

ColumnName DataType [Constraint Cname] Primary Key [Clustered / NonClustered]

Table Level

[Constraint Cname] Primary Key(Col1,Col2,…,Coln)

5. Foreign Key : This constraint is used to create relationship between two tables. While creating the foreign key constraint, we have to give a primary key or unique column as reference to foreign key. Now the foreign key will restrict the user from inserting a value that doesn’t exist in the referenced column.

While specifying the foreign key you can specify “on update” and “on delete” options that will specify the action to be taken on foreign key values when modification was done to primary key column or a primary key row was deleted. This “on update” or “on delete” option will have four options No Action, Cascade, Set Null, and Set Default.

Default option for “on update” as well as “on delete” is no action. When these options are set to no action, it is not possible to update or delete primary key value without first updating or deleting the corresponding foreign key value.

When these options are set to Cascade, then any modification made to primary key value will be automatically made to foreign key value and if a primary key row was deleted then automatically all its dependent foreign key rows will be deleted.

When these options are set to Set Null, then any modification made to primary key value or deletion of a primary key row will automatically set all its dependent foreign key values to null.

When these options are set to Set Default, any modification made to primary key value or deletion of a primary key row will automatically set all its dependent foreign key values to default. If the default value is not specified for the foreign key column, then foreign key value will be set to null.

Syntax :

Column Level

ColumnName Datatype [Constraint Cname] References tablename(columnname)

Table Level

[Constraint Cname] foreign key(Col1,Col2,…,Coln) References Tablename(Col1,Col2,…Coln)

6. Check : This constraint is used to specify a custom condition on a column. When a check constraint is specified at column level, it is not possible to refer to other columns of the table within the condition of the check constraint. When you have to refer to other columns of the table within the condition of the check constraint, then you have to specify the check constraint at table level.

Syntax :

Column Level

ColumnName Datatype [Constraint Cname] check(condition)

Table Level

[Constraint Cname] check(Condition)

Identity Column

Within a table when you want to automatically generate values for a column then you can create that column as identity column by using identity option that has the following syntax.

ColName DataType [Constraint] identity(seed,increment)

select @@Identity Gives the current value of identity

select scope_identity() Gives the current value of identity

select Ident_seed('Student') Gives the seed of the identity

select Ident_Incr('Student') gives the increment of the identity

select ident_Current('Student') Gives the current value of identity

Creating A Table

A table can be created using the create table command that has the following syntax.

Create table TableName

(Column1 Datatype [Constraints Information],

Column2 Datatype [Constraints Information],

Columnn Datatype [Constraints Information]

)

The following example will create a table with the name student with SID, SNAME and COURSE columns.

Create table Student

(SID Smallint constraint SID_PK primary key identity(1001,1),

SNAME varchar(20) not null,

COURSE varchar(25) not null

)

The same table can be created by specifying the primary key at table level as follows.

Create table Student

(SID Smallint,

SNAME varchar(20) not null,

COURSE varchar(25) not null,

Constraint SID_PK primary key(SID)

)

The following example will create a table called MARKS with a foreign key that refers to STUDENT table.

Create table MARKS

(SID Smallint Constraint SID_FK references STUDENT(SID),

C Tinyint Constraint C_CHK Check(C<=100) default 0,

CPP Tinyint Constraint CPP_CHK Check(CPP<=100) default 0,

SQL Tinyint Constraint SQL_CHK Check(SQL<=100) default 0,

TOTAL Smallint,

AVEG Decimal(5,2),

GRADE varchar(30)

)

The same table can be created by specifying constraints at table level as follows.

Create table MARKS

(SID Smallint,

C Tinyint default 0,

CPP Tinyint default 0,

SQL Tinyint default 0,

TOTAL Smallint,

AVEG Decimal(5,2),

GRADE varchar(30),

Constraint SID_FK Foreign Key(SID) references STUDENT(SID),

Constraint C_CHK Check(C<=100),

Constraint CPP_CHK Check(CPP<=100),

Constraint SQL_CHK Check(SQL<=100)

)

Note :

1. To get the list of tables available in the current database you are using, use the following select statement.

Select * from Sysobjects where type=’u’

Here ‘u’ represents the user defined tables. SQL Server also contains system tables. To get the list of system tables, specify ‘s’

2. It is optional to give a name to a constraint when you create it. When didn’t specify a name for the constraint then SQL Server will automatically give a name to the constraint. You can get the details of all constraints available on a table by using the system procedure sp_helpconstraint.

Sp_HelpConstraint ‘TableName’

3. To get a list of all available columns in a table, their data types and constraints information, use the system procedure Sp_help that has the following syntax.

Sp_help ‘tablename’

Altering the Table Structure

You can use Alter Table command to alter the structure of a table, like adding a new column, changing data type of a column, add a constraint , deleting a column or constraint etc.,

Adding New Column

Alter Table TableName Add Col1 Datatype [Constraints],Col2 Datatype [Constraints],…

Changing Data Type of a Column

Alter Table TableName Alter Column Col1 Datatype [null/not null],Col2 DataType [null/not null],….

This syntax can be used to change the data type of a column or add and remove not null constraint on a column.

Adding Constraint to a Column

Alter Table TableName [with check/nocheck] Add [Constraint Constr.Name] Constraint

This Syntax can be used to add constraints like default, unique, primary key, check and foreign key

Adding Default Constraint

Alter Table TableName Add [Constraint Constr.Name] Default Def.value for ColName

Enable or Disable a Constraint

Alter Table TableName Check/NoCheck Constraint Constr.Name

Deleting a Column

Alter Table TableName Drop Column ColName

Deleting a Constraint

Alter Table TableName Drop Constraint Constr.Name

Renaming A Table

Sp_Rename ‘OldName’,’NewName’

Renaming A Column

Sp_Rename ‘TableName.OldName’,’NewName’

Getting information about tables, columns in tables and constraints on tables

select * from information_schema.Tables

select * from information_schema.Columns Where table_name='Emp'

select * from information_schema.table_constraints where table_name='Emp'

Data Manipulation Language (DML)

The commands of SQL that are used to insert data into the database, modify the contents of the database and to delete the data from the database are collectively called as DML. SQL Server provides Insert command for inserting data into the database, Update command to make modifications to the data and Delete command to delete data from the database.

Inserting Data Into A Table

To insert data into a table SQL Server provides insert command and it has the following syntaxes.

1. Insert into tablename values(val1,val2,val3,…,valn)

When you are using this syntax, you must specify a value for every column of the table. Even for a column which allows null values you must specify the value as null to insert null value into that column. If you want to insert the default value for a column then use the keyword default.

Ex 1 : To insert a row into student table, the insert statement will be written as follows.

Insert into student values(1001,’SAI’,’SQL’)

Ex 2 : To insert a row into Marks table, the insert statement will be written as follows. In this example I don’t want to give values for total, average and grade columns. Hence I will specify null as the value for those columns.

Insert into Marks Values(1001,55,77,66,null,null,null)

2. Insert into tablename(Col1,Col2,Col3,…,Coln) values(Val1,Val2,Val3,…,Valn)

By using this syntax you can insert a row into a table without giving values for specified columns. But the columns you exclude must not contain not null constraint. Within the column list after the table name specify the names of columns for which you are providing values and then give values for those columns within the values list.

Ex 1: to insert a row into marks table without giving values for total, average, and grade columns, the insert statement will be written as follows.

Insert into Marks(Sid,c,cpp,sql) values(1001,55,66,77)

3. Insert into tablename select statement

This syntax is used when we have to insert rows from an existing table in to a new table, provided no. of columns and their data types match in those two tables.

Select * into Tablename From Tablename Syntax is used create a new table from existing table.

Updating Data In The Table

When you want to make modifications to the data available in the table, you have to use update command. Update command has the following syntax.

Update tablename set column1=val1,column2=val2,….,column=valn [where condition]

Specifying where clause is optional and when you didn’t specify the where clause then the modification will be made to every row in the table.

Ex 1: To update the course of a student with sid 1002 to SQL, the update command will be as follows.

Update Student set course=’SQL’ where sid=1002

Ex 2: To update rows in marks table by calculating total, average columns, the update statement will be as follows.

Update Marks Set Total = C+Cpp+Sql, Average = (C+Cpp+Sql)/3

Ex 3: To update marks table by calculating grade, the update statement will be as follows. SQL server provides case statement to check for a condition and then execute the statements within update command and this update statement will use case to update grade based on average marks of the student.

Update Marks set Grade = case

When Average>=90 then ‘DISTINCTION’

When Average>=70 then ‘FIRST CLASS’

When Average>=55 then ‘SECOND CLASS’

When Average>=35 then ‘THIRD CLASS’

Else ‘FAIL’

End

Note : SQL Server supports calculated columns. Calculated columns are the columns for which values are calculated automatically based on expressions given for those columns during the table creation. For example to create marks table with total and average as calculated columns, the create table statement will be as follows.

Create table Marks

(SID smallint constraint SID_Fk references Student(SID),

C Tinyint,

Cpp Tinyint,

SQL Tinyint,

Total as C+Cpp+SQL,

Average as (C+Cpp+SQL)/3,

Grade varchar(30)

)

Deleting Data From The Table

When you want to delete a row or rows from the table then you can use delete command. Delete command has the following syntax.

Delete [From] tableName [where Condition]

Here also specifying where clause is optional and when you didn’t specify the where clause, every row in the table will be deleted.

Ex 1: To delete a row from student table, whose SID is 1002, the delete statement will be as follows.

Delete Student Where SID=1002

Ex 2: To delete all rows from marks table, the delete statement will be as follows.

Delete Marks

Truncate Command

For deleting rows from a table you can also use truncate command. Differences between delete and truncate commands are as follows.

Delete	Truncate
You can delete only specified rows using where clause	It is not possible to delete specified rows from the table as this command doesn’t support where clause and this command is used only when you want to delete all rows from a table.
Deletes rows one by one	Deletes rows page by page. Hence deletion will be fast.
Deleted rows can be rollback.	Deleted rows can’t be rollback.
Memory will not be released to server	Memory will be released to server

Syntax : Trucate table TableName

Retreiving Data

A statement that requests data from the database is called as a query. In SQL select statement is used to retrieve data from the database and hence the select statement is called as a query. Select statement has the following syntaxes.

1. Select * From TableName

This syntax is used to retrieve every row from the table with information from every column of the table. Here * represents “all columns”.

Examples:

i. Display The Details of all employees in the company

Select * From emp

ii. Display the details of all students

Select * from Student

2. Select Column1,column2,column3,… From TableName

This syntax is used to retrieve the information from only specified columns of the table from every row of the table.

Examples:

i. Display Employee no,name,job and salary for every empoloyee

select empno,ename,job,sal from emp

ii. Display sid and sname from student

select sid,sname from student

3. Select */ColumnList From TableName Where Condition

This syntax is used retrieve only specified rows from table. The given condition will be verified with every row and only the rows that satisfy the given condition will be displayed in the output.

Examples:

i. Display the details of employees working in department 30

Select * from emp where deptno=30

ii. Display the details of employees working as manager

Select * from emp where job=’manager’

iii. Find employees whose salary is more than 2000 and less than 3000

Select * from emp where Sal>2000 and sal<3000

4. Select distinct ColumnList From TableName [Where Condition]

Distinct is used to eliminate duplicate values in the output of a select statement. Distinct can be used only once in a select statement and it must be immediately after select key word. When you specify a single column in the selection list after distinct then duplicates will be eliminated in that column. When you specify multiple columns in the selection list after distinct then duplicates will be eliminated in the combination of values of specified columns.

Examples :

i. Find Department nos in which employees are working

Select Deptno from Emp

This query will display Department nos 10,20 and 30 with duplicates. To display the result without duplicates we have to write the query as

Select Distinct Deptno from emp

5. Select [Distinct] */ColumnList From TableName [Where Condition] Order By ColumnName Asc/Desc

Order By clause is used in select statement to arrange the rows in the out put in either ascending or descending order of specified columns In the order by clause. In order by clause you can specify more than one column and when you specify more than one column, first the rows are arranged in specified order of first column in order by clause and then if more than one row has same value in that column then those rows will be arranged in specified order of second column in order by clause and so on.

Examples:

i. Display all employees in the order of highest salary to lowest salary

Select * from emp order by sal desc

ii. Display all employees in alphabetical order of their name

Select * from emp order by ename

6. Select ColumnName AliasName, ColumnName AliasName,… From TableName

Within the select statement you can give alias names for the columns so that column names will be changed in the output of the select statement. When alias name is more than one word then it is compulsory to include it in double quotes. Generally alias names are used for the expressions like “sal *12”

Examples:

i. Display empno,name,job,salary and annual salary for every employee

Select empno,ename,job,sal,sal*12 as annualsal from emp

Predicates

SQL supports various key words and operators that can be used in where clause of select statement and these key words and operators are called as predicates. Among the predicates supported by SQL, Four predicates are as follows.

Between … And : This predicate is used to verify whether the given value exists in given range of values. This predicate can be used with numeric type of data as well as date type of data.

Examples:

i. Find all employees whose salary is more than 2000 and less than 3000

Select * from emp where sal between 2000 and 3000

ii. Find all employees who are joined in the company in the year 1982

Select * from emp where sal between ‘1/1/1982’ and ‘12/31/1982’

In : This predicate is used to verify whether the given value exists in a given list of values. This can be used with numeric, character and date type of data.

Examples:

i. Find all employees whose salary is either 800 or 1250 or 1600

Select * from emp where sal in(800,1250,1600)

ii. Find all employees who are working as either manager or clerk or analyst

Select * from emp where job in (‘manager’,’clerk’,’analyst’)

Like : this predicate is used to verify for a specific pattern in character columns. This is used only with character type of data. With the like predicate you have to use two wild characters % and _ (Underscore).

Examples:

i. Find all employees whose name starts with ‘S’

Select * From emp Where Ename like ‘S%’

ii. Find all employees whose name ends with ‘E’

Select * from emp where ename like ‘%E’

Is Null : This predicate is used to verify for a null value in a given column.

Examples:

i. Find all employees who are not drawing commission

Select * from emp where comm Is null

Built In Functions

As in other languages like C and C++, SQL also provides Built in functions. Built in functions in SQL are classified into following categories.

1. Scalar Functions

2. Aggregate Functions

3. Ranking Functions

Scalar Functions : The built in functions in SQL Server that work on a single value are called as scalar functions. Scalar functions are again classified into following categories based on data type on which they work.

a) Numeric Functions

b) String Functions

c) Date Functions

d) Conversion Functions

e) System Functions

Numeric Functions : The scalar functions of SQL that work on numeric type of data are called as numeric functions. Numeric functions in SQL are as follows.

Abs(n) : Returns absolute value of the given n i.e. n value without any sign.
Ceiling(n) : Returns smallest integer greater than or equal to n.
Floor(n) : Returns Largest integer less than or equal to n.
Radians(n) : Converts the given n in degrees to radians.
Degrees(n) : Converts the given n in radians to degrees.
Exp(n) : Returns e raised to the power of n. e is exponential whose value is constant and is 2.713
Log(n) : Returns natural logarithm of n. i.e. base e logarithm.
Log10(n) : Returns base 10 logarithm of n.
Power(m,n) : Returns m raised to the power of n.
Square(n) : Returns Square of given n.
Sqrt(n) : Returns Square Root of given n.
Sin(n) : Returns sine value of given n in radians.
Cos(n) : Returns cosine value of given n in radians.
Tan(n) : Returns tangent value of given n in radians.
Sign(n) : Return -1 if n is negative, 1 if n is positive and 0 if n is zero.
Pi() : Return mathematical constant pi value i.e. 3.14
Round(n,p,t) : Rounds the given in n to p decimal places. If t is specified as 1 then it truncates n to p decimal places instead of round the value.

String Functions : The built-in functions of SQL that work on string type of data are called as string functions. String functions in SQL are as follows.

ASCII(char) : Converts the specified character to the equivalent ascii code.
Char(int) : Converts ascii code to the equivalent character.
CharIndex(s1,s2,[pos]) : returns the starting position where the partial string s1 first occurs in the string s2. Returns zero if s1 does not exist in s2.
Lower(S1) : Converts all uppercase letters of the string s1 to lower case letters.
Upper(s1) : Converts all lowercase letters of the string s1 to upper case letters.
Ltrim(s1) : removes leading blank spaces in the string s1.
Rtrim(S1) : Removes trailing blank spaces in the string s1.
Reverse(S1) : Reverses the string S1.
Right(S1,Len) : returns last Len characters from the string S1.
Left(S1,Len) : returns first len characters from the string S1.
Soundex(a) : Returns how the given string is pronounced in a four character soundex code.
Stuff(s1,a,n,s2) : Replaces the partial string s1 with the partial string s2 starting at position a, replacing n no. of characters.
Substring(S1,a,len) : creates a partial string from string s1 starting at the position a with a length of len.

Date Functions : The built-in functions of SQL that work on date type of data are called as date functions and date functions in SQL server are as follows.

GetDate() : Returns the current system date and time.
DatePart(item,D) : returns the specified item of a date D as an integer.
DateName(item,D) : returns the specified item of the date D as a string.
DateDiff(item,D1,D2) : calculates the difference between the two dates D1 and D2 and returns the result as an integer in units specified by the item.
DateAdd(item,n,D) : Adds the number n no. of units specified by the item to the given date D and returns a date.

Conversion Functions : The Built-In functions of SQL Server that are used to convert one type of data to another are called as conversion functions and conversion functions in SQL Server are as follows.

Cast(a as type[(length)]) : converts an expression a into the specified data type type.
Convert(type[(length}],a) : Equivalent to cast, but the arguments are specified differently.

System Functions : The SQL Server system functions provide extensive information about database objects.

Object_ID(objname) : returns the identifier of the database object objname.
Object_name(obj_id) : returns the name of the database object with id obj_id.
Col_Name(Obj_Id,S_Id) : returns the name of the column belonging to the object obj_id with the identifier s_id.
Col_Length(obj,Col) : returns the length of the column belonging to a database object obj.
Datalength(s1) : calculates the length of the result of the expression s1.
DB_Id(Db_name) : returns the id of the database db_name.
DB_Name(Db_id) : returns the name of the database with id Db_id.
User_Id(username) : returns the id of specified user name.
user_name(uid) : returns the name of the user with id uid.
Current_TimeStamp : returns the current timestamp of the database.

Aggregate Functions : The Built-In Functions of SQL Server that operate on a set of values are called as aggregate functions. Aggregate functions are again classified into following categories.

Convenient Aggregate Functions
Statistical Aggregate Functions
Super Aggregates

1. Convenient Aggregate Functions :

o Sum(Col) : Returns the sum of all values in the specified column.

o Avg(Col) : Returns average of all values in the given column.

o Max(Col) : Returns the highest value among all values in the given column.

o Min(Col) : Returns the smallest value among all values in the given column.

o Count(*)/Count_Big(*) : Returns the total no. of rows in the given table.

o Count(Col)/Count_Big(Col) : Returns the no. of non-null values in the given column.

2. Statistical Aggregate Functions :

o Var(Col) : Returns Variance of all values in the given column.

o Varp(Col) : Returns Variance of population of all values in the given column.

o Stdev(Col) : Returns standard deviation of all values in the given column.

o Stdevp(Col) : Returns Standard Deviation of population of all values in the given column.

Group By : Group By is used to group the rows of table based on values of a given column and applies the aggregate function on each group separately.

Examples:

i. calculate sum of salaries of employees department wise

Select Deptno,Sum(Sal) from emp group by Deptno

In the above query group by will divide the table in to groups based on deptno and then calculates sum(sal) for each group separately, which will give the sum of salaries of employees department wise.

ii. Calculate sum of salaries of employees job wise

Select Job,Sum(sal) from emp group by job

iii. Find the number of employees working in each department

Select Deptno,Count(*) from emp group by Deptno

iv. Find the total salary paid to employees job wise In each department

Select Deptno,Job,Sum(Sal) from emp group by Deptno,job

Rule : A rule to be followed when working with group by is the columns that are selected in the select list except aggregate functions must be in group by.

Having : Having is used to check the condition that contains an aggregate function and in this case it is not possible to use where clause. Because where clause can check a condition without any aggregate function but not a condition with aggregate function. For example if you want to find the departments with three or more employees then the query will be as follows.

Select Deptno,Count(*) From Emp group by Deptno having Count(*)>=3

In the above query condition is Count(*)>=3. This contains an aggregate function. Hence we must use having instead of where clause.

Find the Jobs whose average salary is more than 2000

Select Job,Avg(Sal) from emp group by job having Avg(sal)>2000

Find the Departments whose average salary is more than 2000 and no. of employees

more than 3.

Select Deptno , Avg(Sal),Count(*) from emp group by Deptno

Having avg(sal)>2000 and count(*)>3

Rule : A Rule to follow when using having clause is a corresponding group by is must.

Super Aggregates : SQL Server provides Two super aggregates Cube and Rollup.

Roll Up : Roll up is used to calculate sub totals at the end of each group based on values of first column in group by when you group the data on more than one column.

Cube : Cube is used to calculate sub totals at the end of each group based on values of second column in group by along with the result of rollup when data is grouped on more than one column in group by.

Roll up and Cube can be used only with group by. For example if you want to calculate sub totals at the end of each department when grouping data on both Deptno and Job, then the following query is used.

Select Deptno, Job, Sum(Sal) from emp group by Deptno,Job with roll up / with cube

COMPUTE Clause : The compute clause uses aggregate functions to calculate summary values that appear as additional rows in the result of a query. The aggregate functions used with the compute clause are referred to as row aggregate functions.

The compute clause has an optional BY portion. BY defines the grouping form of the result. If BY is omitted, the row aggregate function is applied to all rows of a result query. The ORDER BY clause is required if the COMPUTE clause with BY is used.

Example :

Display Employee Details Along with Total salary department wise

Select * from Emp order by Deptno Compute Sum(sal) by Deptno

OVER Clause : OVER Clause can be used to group the data like GROUP BY. The main difference between the use of the GROUP BY clause and grouping using the OVER clause is that the OVER clause displays each of the rows from a group separately, while the GROUP BY clause displays only one row for each group.

Example :

Display Employee Details Along with Total salary department wise

Select *,Sum(Sal) over(partition by deptno) from emp

RANKING FUNCTIONS

SQL Server 2005 defines several functions that are categorized as ranking functions, i.e., functions that return a ranking value for each row in a partition group. The system supports following ranking functions.

1. RANK() : This function is used to return a number that specifies the rank of the row among all rows. The RANK function uses logical aggregation. In other words, if two or more rows in a result set have same value in the ordering column, they will have the same rank.

Example :

Display employee details along with a rank based on salary

Select empno,ename,job,sal,rank() over(order by sal desc) as Rank from emp

2. DENSE_RANK() : This function works same as Rank(), except that it will not skip a rank when two or more rows got the same rank.

Example :

Display employee details along with a rank based on salary

Select empno,ename,job,sal,Dense_rank() over(order by sal desc) as Rank from emp

2. ROW_NUMBER() : It returns the sequential number of a row within a result set, starting at 1 for the first row.

PARTITION BY : Ranking functions can be applied to partitions by using partition by clause within the OVER() clause along with ORDER BY.

Example :

Display Employee details along with a rank department wise

Select empno,ename,job,sal,Dense_rank() over(partition by Deptno order by Sal Desc) as Rank

from emp

TOP n Clause : This clause specifies the first n rows of the query result that are to be retrieved. The TOP n clause can also be used with the additional PERCENT option. In that case, the first n percent of the rows are retrieved from the result set. The additional option WITH TIES specifies that additional rows will be retrieved from the query result if they have the same value in the ORDER BY column as the last row that belongs to the displayed set.

Example :

i. Find Top3 salaried employees

Select Top 3 empno,ename,job,sal from emp order by sal desc

ii. find Top 10% salaried employees

Select Top 10 Percent Empno,ename,job,Sal from emp order by sal desc

SET OPERATORS

SQL Server supports the following three set operators that connect two or more queries.

1. UNION

2. INTERSECT

3. EXCEPT

UNION : The result of the UNION of the two sets is the set of all elements appearing in either or both of the sets by eliminating duplicate values. If UNION ALL is used, all resulting rows, including duplicates, are to be displayed.

Example :

Find jobs available in departmenents 10,20

Select Job From Emp Where Deptno=10

Union

Select Job From Emp Where Deptno=20

INTERSECT : The intersection of two tables is the set of rows belonging to both tables.

Example :

Find jobs available Both in departmenents 10 and 20

Select Job From Emp Where Deptno=10

Intersect

Select Job From Emp Where Deptno=20

EXCEPT : This finds the difference of two tables. The difference of two tables is the set of all rows, where the resulting rows belong to the first table but not to the second one.

Example :

Find jobs available in departmenent 10 And not in 20

Select Job From Emp Where Deptno=10

Except

Select Job From Emp Where Deptno=20

Rules

All the select statements must select same number of columns
The corresponding columns in all select statements must be of same type

JOINING

The process of combining data from more than one table using a single select statement is called as joining. Within a relational database data will not be stored in a single table. Hence join is needed whenever we have to retrieve data from more than one table. Joining in SQL Server is classified as follows.

EQUI JOIN : Joining more than one table by using a join condition that uses = operator is called as equi join.

Example :

Display Employee Details along with department details in which employee is working.

Select * From Emp E join Dept D on E.Deptno=D.Deptno

NATURAL JOIN : A join is called as natural join when it satisfies the following.

1. Join is Equi join

2. All common columns in the tables that are joined are used in Where clause

3. Only one set of common columns is displayed in the output

Example :

Display Employee Details along with department details in which employee is working.

Select E.*,Dname,Loc From Emp E join Dept D on E.Deptno=D.Deptno

OUTER JOIN : The join statement that displays the data that doesn’t satisfy the given join condition along with the data that satisfies the condition is called as outer join. Outer join is again three types.

Left Outer Join : the outer join that displays rows from LHS table that does not contain a corresponding row in RHS table is called as Left Outer Join.
Right Outer Join : the outer join that displays rows from RHS table that does not contain a corresponding row in LHS table is called as Right Outer Join.
Full Outer Join : The outer join that displays rows from both the tables that doesn’t contain a corresponding row in the opposite table is called as full outer join.

Example :

Display Employee Details along with department details in which employee is working. Also display the details of departments in which there are no employees.

Select * From Emp E right outer join Dept D on E.Deptno=D.Deptno

THETA JOIN : The join operation that uses a condition that contains an operator other than = is called as theta join.

Example :

Display Employee Details along with Grade of employee based on salary

Select *,grade From Emp join salgrade on Sal between losal and hisal

CROSS JOIN : The join statement without any join condition is called as cross join. The result of this cross join is called as Cartesian product.

Example :

Display Employee Details by associating every employee with every department

Select * From Emp E Cross join Dept D

SELF JOIN : The join statement that joins a table to it self is called as self join.

Example :

Display Employee Details along with his/Her manager name

Select E.Empno,E.ename,E.Job,E.Sal,E.Mgr,M.Ename

From Emp E join Emp M on

E.Mgr=M.Empno

Rule : A rule to be followed when writing a join statement with SQL server Syntax is no. of join conditions must be one less than no. of tables on which you perform join.

SUB QUERIES

A statement that requests data from the database is called as a query. Select is used to request data from the database and hence select statement is called as a query. A select statement within another select statement is called as a sub query. Sub queries are classified as follows.

Single Row Sub Queries
Multi Row Sub Queries
Nested Sub Queries
Co-related sub queries

SINGLE ROW SUB QUERIES : The sub query that returns only one row is called as single row sub query.

Example :

i. Find The Employees Working In Sales Department.

Select * From Emp where Deptno=

(Select Deptno From Dept Where Dname=’Sales’)

ii. Find The Employee Who is drawing highest salary.

Select * from emp where sal=

(Select max(sal) from emp)

MULTI ROW SUB QUERIES : The Sub query that returns more than one row is called as multi row sub query. When a sub query returns more than one row then it is not possible use the operators like =,<,>,<=, and >=. To make this possible SQL Server provides two operators, Any and All. “Any” operators returns true when the given condition is true with at least one value returned by the sub query and “All” operator will return true only when the condition is true with every value returned by the sub query.

Example :

i. Find highest salaried employees department wise

Select * from emp where sal in

(Select max(sal) from emp group by deptno)

ii. Find Employees not working in dept 30 and drawing salary more than any

one employee in dept 30.

Select * from Emp where Deptno!=30 and sal> Any

(Select Distinct sal from emp where deptno=30)

iii. Find Employees not working in dept 30 and drawing salary more than all

employees in dept 30.

Select * from Emp where Deptno!=30 and sal> All

(Select Distinct sal from emp where deptno=30)

NESTED SUB QUERIES : The sub query that contains another sub query within it is called as nested sub query.

Example :

Find Employees whose salary is more than average salary of sales Dept.

Select * from emp where sal >

(Select Avg(sal) from emp where deptno=

(Select Deptno from Dept where Dname=’Sales’))

CO-RELATED SUB QUERIES : The sub query that refers a column of the outer query within its condition is called as co-related sub query. SQL Server provides two operators that can be used only with co-related sub queries, Exists and NotExists. “Exists” returns true only when the co-related sub query returns at least one row and “NotExists” will return true only when the co-related sub query doesn’t return any rows.

Example :

i. Find Employees whose salary is more than average salary of the dept in which he is working.

Select * from Emp E where Sal >

(Select Avg(sal) from Emp S where E.Deptno=S.Deptno)

ii. Find Employees To Whom At least one employee is Reporting.

Select * From emp M where exists

(Select * From Emp e where M.Empno=E.Mgr)

iii. Find Departments in which there are no employees

Select * From Dept D where not exists

(Select * From emp Where D.Deptno=E.Deptno)

INDEXES

An index in SQL Server is similar to an index in a book. We can find a topic in a book very fast with the help of an index. In the same way if an index is available in SQL Server, then data retrieval will be very fast. Hence the main purpose of an index is to speed up the data retrieval. An index is maintained by SQL server in the form of a B-Tree data structure. To create an index, the following syntax is used.

Create [Unique] [Clustered/NonClustered] index idxname on tablename(Col1,Col2,…)

When we use Unique keyword during the creation of index, then along with the index unique constraint will also be created on that column.

When an index is a clustered index, then the physical order of rows in table will be in the same order of rows in index and when an index is an unclustered index, then the physical order of rows in the table will not be in the order of rows in the index.

When an index is created on a single column, then the index is called as single column index and when the index is created on more than one column, then the index is called as a multi column index or composite index.

Example :

i. Create an index on deptno column of emp table.

Create Index DnoIDX on Emp(Deptno Asc)

ii. Create An Index On Deptno And Job Columns Of Emp Table.

Create Index DnoJobIDX on Emp(Job Asc,Deptno Desc)

SQL Server will use index only in the following situations

The column on which index was created is referred in where clause.
If the index is created on more than one column, all the columns on which index was created must be referred in where clause.

Altering An Index

After creating index you can alter the index using alter index command that has the following syntax.

Syntax : Alter Index IdxName on TableName Rebuild/Reorganize/Disable

Rebuild will rebuild the entire index.

Reorganize will reorganize the leaf level nodes of Index

Disable will disable the index and to enable the index use rebuild option.

Deleting an Index

To Delete an index use drop index command as follows.

Drop Index IdxName

VIEWS

A view is a logical object that doesn’t contain data directly. A view is not an independent object and is created from a table or another view. The main purpose of a view is as follows.

1. To restrict the access to specific rows and or columns in the table.

2. To restrict the insertion and updation to only specified range of values.

3. To hide the complexity of a complex query like join or subquery.

Once a view is created you can use it like a table and you can perform any DML operation on that view as you perform on table. But any modification made to the view will be done in the table from which the view was created and whenever you select data from the view, the select statement written for the view will be executed and data is retrieved from the base table of the view.

Creating A View :

Create view viewname(Col1,Col2,…) [with encryption] as select statement [with check option]

Example :

Create a view that will provide access to only dept 10 rows from emp table

Create View Emp10 As Select * From emp Where Deptno=10

If we create a view without with check option clause, then insertion and updation can be done for the rows that doesn’t satisfy the condition specified in where clause of select statement of the view and if a view is created with with check option clause then insertion and updation of rows in the view is not possible if the row fails to satisfy the condition specified in where clause of the select statement of the view.

Complex View

A view is called as a complex view if it satisfies any of the following conditions.

If the view is created from a select statement that combines the data from more than one table.
If the select statement of the view contains distinct or group by.
If the select statement of the view contains an expression like Sal*12 as a column.
if the Select statement contains Aggregate functions.

Performing DML operations is not possible on complex view. But user can select data from the complex view.

Example :

Create a view that will contain data of employees along with department details in which employee is working.

Create View EmpDept as Select E.*,Dname,Loc from emp join dept

Where e.deptno=d.deptno

Altering a View

A view can be altered by using Alter view command when you want to change the definition of the view.

Syntax : Alter View ViewName[(Col1,Col2,…)] As Select Statement [With Check Option]

Deleting A View

Drop view viewname

Getting Details of a View

select * from information_schema.views

getting list of view available on a table

select * from information_schema.view_table_usage where table_name='Emp'

getting definition of a view

sp_helptext ‘viewname’

TRANSACTION PROCESSING

A series of changes made to one or more tables of the database is called as a transaction. When we make changes to the database by creating a transaction, any changes made to the database will not be made permanent to the database and user will have the choice to cancel those changes or make those changes permanent. For transaction processing SQL Server provides the following commands.

1. Begin Transaction : This command will start a transaction.

2. Commit Transaction : This command will make changes in the current transaction permanent and ends the transaction.

3. Rollback Transaction : This command will cancel the changes in the current transaction and ends the transaction.

4. Save Transaction : This command will create a save point that will divide the transaction in to more than one part so that user can commit one part while rollback the other part. When user rollback the transaction to a save point, all the changes made to the database prior to the save point will be committed while all the changes after the save point are rollback.

During the transaction processing, SQL Server will use log files to record the changes and uses the information in log file to commit or rollback the changes in current transaction. If a transaction was started and there is system failure before the transaction was committed or rollback, then all the changes in the current transaction will be automatically rollback. Whenever a change was made to the database in a transaction, before image of the table and after image of the table are written to the log file. In case transaction was committed, after image will be used to make the changes in current transaction permanent to the database other wise before image will be used to cancel the changes made to the database.

PROCEDURAL STATEMENTS

SQL is a non-procedural language and hence it is very easy to work with SQL. But solving some complex queries is not possible is not possible using SQL. Hence procedural features are provided for SQL, which is called as PL/SQL.

Block : A set of statements written within Begin and End statements is called as a block.

Begin

-----

End

Print : Print command is used to print any output to the out put window.

Print ‘Out put To Display To The User’

Declaration : to declare variables within a block use Declare key word and a variable in SQL Server must be prefixed with @

Declare @Var1 Datatype, @Var2 Datatype,…

Setting Value : To set value for a variable, use set statement.

Set @Var=Value

If condition

Begin

Statements

End

If Condition

Begin

Statements

End

Else if Condition

Begin

Statements

End

Else if condition

Begin

Statements

End

Else

Begin

Statements

End

WHILE

While Condition

Begin

Statements

End

Examples :

i. This examples adds two numbers and prints the sum

Begin

Declare @A int,@B int, @S int

Set @A=10

Set @B=20

Set @S=@A+@B

Print ‘Sum is ‘ + cast(@S as varchar(5))

End

ii. This example will determine whether an integer is even or odd

Begin

Declare @N int

Set @N=5

If @N%2=0

Print ‘Even Number’

Else

Print ‘Odd Number’

End

iii. This Example will print integers from 1 to 10

Begin

Declare @N int

Set @N=1

While @N<=10

Begin

Print @N

Set @N=@N+1

End

STORED PROCEDURES

SQL Server supports the creation of user defined functions as well as procedures, which are called as stored Subprograms. An user defined function is a stored subprogram that will return a value back to the calling location. To create a function, the following syntax is used.

Create Function FunctionName(@Param1 Datatype, @Param2 Datatype, …) Returns Datatype [with encryption] as

Begin

Statements

Return Value

End

Sp_Helptext System procedure can be used to get the source code written for a function or procedure.

SP_HelpText ‘ProcName’

When you create the stored sub program with with encryption then source code will not be displayed and will be encrypted.

To execute an user defined function, you can use select statement as follows

Select Dbo.Functionname(Arg1,Arg2,…)

Example :

i. Create a Function that will calculate Sum of three integers

Create Function Total(@A int,@B int, @C int) returns int as

Begin

Return @A+@B+@C

End

ii. Create A Function That Will Generate New Deptno Automatically.

Create Function NewDno() returns int as

Begin

Declare @NDno int

Set @NDno=(Select isnull(max(deptno),0)+10 from dept)

Return @NDno

End

To Delete a function, use Drop Function Command as follows.

Drop Function FunctionName

A procedure is a stored subprogram that will not return a value back to the calling location and syntax for creating a procedure is as follows.

Create Procedure ProcedureName(@param1 Datatype, @Param2 Datatype,…) [with encryption] as

Begin

Statements

End

To execute a procedure, use execute command as follows.

Execute ProcName Arg1 , Arg2, Arg3, …

Example :

i. Create A Procedure that will insert a row into Dept table.

Create Procedure InsertDept(@Dno int,@Dn varchar(30),@L varchar(30)) as

Begin

Insert into Dept values(@Dno,@Dn,@L)

End

ii. Create A Procedure To Update A Row Of Dept Table.

Create Procedure UpdateDept(@Dno int, @Dn varchar(30),@l varchar(30)) as

Begin

Update Dept Set Dname=@Dn,Loc=@L where Deptno=@Dno

End

iii. Create A Procedure To Delete A Row From Dept table.

Create procedure DelDept(@Dno int) As

Delete Dept Where Deptno=@Dno

To Delete a procedure, use Drop Procedure command as follows.

Drop Procedure Procedurename

Default Arguments

A procedure can be created with default arguments. A default argument is an argument that is initialized within the procedure creation. When an argument is created as default argument, it is optional to pass a value to that argument during function call and if you don’t pass a value then default value will be used other wise the value you pass will overwrite the default value. Advantage is a procedure can be called with variable number of arguments. Functions doesn’t support default arguments.

Example :

This example will create a procedure that can be called with 2 or 3 or 4 or 5 integers to calculate Sum.

Create procedure MySum(@A int,@B int, @C int=0,@D int=0,@E int=0) As

Begin

Print @A+@B+@C+@D+@E

End

Execute MySum 10,20

Execute MySum 10,20,30

Execute MySUm 10,20,30,40

Execute mySum 10,20,30,40,50

Output Parameters

In SQL Server Parameters of functions and procedures are classified into input parameters and output parameters. By default every parameter is an input parameter. Any changes made to input parameters within the function or procedure will not reflect in arguments passed to them. But any changes made to output parameters will reflect in arguments.

Example : This example will create a procedure Swap that will swap two integers.

Create procedure Swap(@X int output, @Y int output) As

Begin

Declate @T int

Set @T=@X

Set @X=@Y

Set @Y=@T

End

To execute this procedure we have to create a block as follows.

Begin

Declare @A int,@B int

Set @A=10

Set @B=20

Print ‘Before Swap A = ‘ + cast(@A as varchar(3)) + ‘ B = ‘ + cast(@B as varchar(3))

Swap @A output,@B output

Print ‘After Swap A = ‘ + cast(@A as varchar(3)) + ‘ B = ‘ + cast(@B as varchar(3))

End

Cursors

Cursors are used within a stored procedure when you want to access the rows of a table in a sequence. Actually we can access only one row at a time within a stored procedure. But with the help of cursors we can access the rows of a table one by one sequentially. To work with cursors we have to follow the following steps.

Cursor Declaration : first we have to declare the cursor. During the declaration a name was given to the cursor and a select statement is associated with the cursor.

Declare Cursorname Cursor [forward_only/Scroll] [static/dynamic/keyset]

for select statement

Opening Cursor : Before using the cursor, cursor must be opened. When we open the cursor, the select statement associated with the cursor will be executed and the returned rows will be stored in buffer and cursor will point to this buffer.

Open CursorName

Fetching Rows : Retrieving a row in the buffer pointed by cursor into local variables is called as fetching. As it is not possible to make changes to the data within the buffer, first they must be copied to the local variables. You can verify whether fetch was success or not by using the system variable @@FETCH_STATUS. If fetch was success this variable will contain “0” other wise a negative value.

Fetch Next / Prior / First / Last / Absolute n / Relative n from Cursorname To Local variables list

Closing Cursor : After the work with cursor was finished, cursor must be closed. When the cursor was closed, it is not possible to fetch the rows. But you can reopen the cursor to fetch rows.

Close CursorName

Deallocating Cursor : Finally you can deallocate cursor so that memory resources associated with the cursor will be released.

Deallocate Cursorname

Example : This example will Read one by one record from Emp table and increments salary based on job

Create procedure Increment as

Begin

Declare @Eno int,@J varchar(30),@S decimal(7,2)

Declare MyCur Cursor for select empno,job,sal from emp

Open MyCur

Fetch next from mycur into @Eno,@J,@S

While @@Fetch_Status=0

Begin

If @J=’President’

Set @S=@S+5000

Else if @J=’Manager’

Set @S=@S+3000

Else if @J=’Analyst’

Set @S=@S+2000

Else if @J=’Salesman’

Set @S=@S+1500

Else

Set @S=@S+700

Update Emp set Sal=@S where Empno=@Eno

Fetch Next From MyCUr into @Eno,@J,@S

End

Close Mycur

Deallocate Mycur

End

TRIGGERS

A trigger is like a stored procedure stored within the database. But unlike stored procedure, the trigger will be executed automatically based on the DML event specified for the trigger during trigger creation.

While working with the triggers SQL server will automatically create two virtual tables inserted and deleted. Inserted table will contain new values of the row and deleted table will contain old values of the row.

Constraints within SQL Server are classified into declarative integrity constraints and procedural integrity constraints. Declarative integrity constraints are the constraints that can be specified during table creation and procedural integrity constraints are the constraints that are not possible to specify during table creation and for the specification of procedural integrity constraints triggers are used. Purpose of trigger is

To Create procedural integrity constraints
To record Audit information of a table.
To Make DML operation possible on complex view

Trigger creation has the following syntax

Create trigger trigger name

On Table/View name

For/After/Instead of

Insert / Update / Delete

Begin

Statements

End

Examples :

1. This example will create a trigger that will restrict the user from performing DML operation on Dept table on Sunday.

Create trigger Sunday

On Dept

For insert,update,delete

As begin

Declare @Day varchar(30)

Set @Day=(Select datename(dw,getdate()))

If @Day=’sunday’

Begin

Print ‘Transaction Are Not Allowed on Sunday’

Rollback Transaction

End

2. This example will create a trigger on dept table that will record audit information of dept table in to another table called auditdept.

Create trigger Audit on Dept for insert,update,delete as begin

Declare @Odno int,@ODn varchar(30),@OL varchar(30)

Declare @Dno int,@Dn varchar(30),@L varchar(30)

Set @Odno=(Select Deptno from Deleted)

Set @Odn =(select Dname from Deleted)

Set @OL=(Select Loc From Deleted)

Set @Dno=(Select Deptno From Inserted)

Set @Dn=(Select Dname From Inserted)

Set @L=(Select Loc From Inserted)

Insert into AuditDept values(@ODno,@ODn,@OL,@Dno,@Dn,@L,Getdate())

End

Instead of triggers

When a view is created as complex view, DML operations will not be possible on that view. Instead of triggers are used to make DMLoperations possible on a complex view.

Example: This example will create trigger on EMPDEPT view, which a complex view created from emp and dept tables and will make insert possible on this view.

Create Trigger InsteadInsert on Empdept instead of insert as

begin

Insert into emp select empno,ename,job,mgr,hiredate,sal,comm.,deptno from inserted.

End

Deleting A Trigger

To Delete a trigger use drop trigger command as follows

Drop trigger TriggerName

To get the list of trigger created on a table use the system procedure SP_HELPTRIGGER

SP_HELPTRIGGER ‘TableName’

To get the code written for either a trigger or function or procedure or view, use SP_HELPTEXT system procedure.

SP_HELPTEXT ‘procedurename’

Microsoft SQL Server 2005 Overview

SQL Server Data Platform

SQL Server is a comprehensive, integrated end-to-end data solution that empowers users across your organization by providing them with a secure, reliable, and productive platform for enterprise data and business intelligence (BI) applications. SQL Server 2005 delivers powerful, familiar tools to Information Technology professionals as well as to information workers, reducing the complexity of creating, deploying, managing, and using enterprise data and analytical applications on platforms ranging from mobile devices to enterprise data systems. Through a comprehensive feature set, interoperability with existing systems, and automation of routine tasks, SQL Server 2005 provides a complete data solution for enterprises of all sizes. Figure 1 shows the layout of the SQL Server 2005 data platform.

Figure 1: The SQL Server 2005 Data Platform

The SQL Server data platform includes the following tools:

· Relational database: Secure, reliable, scalable, highly available relational database engine with improved performance and support for structured and unstructured (XML) data.

· Replication Services: Data replication for distributed or mobile data processing applications, high systems availability, scalable concurrency with secondary data stores for enterprise reporting solutions, and integration with heterogeneous systems, including existing Oracle databases.

· Notification Services: Advanced notification capabilities for the development and deployment of scalable applications that can deliver personalized, timely information updates to a variety of connected and mobile devices.

· Integration Services: Extract, transform, and load capabilities for data warehousing and enterprise-wide data integration.

· Analysis Services: Online analytical processing (OLAP) capabilities for the rapid, sophisticated analysis of large and complex datasets using multidimensional storage.

· Reporting Services: A comprehensive solution for creating, managing, and delivering both traditional, paper-oriented reports and interactive, Web-based reports.

· Management tools: SQL Server includes integrated management tools for advanced database management and tuning as well as tight integration with tools such as Microsoft Operations Manager (MOM) and Microsoft Systems Management Server (SMS). Standard data access protocols drastically reduce the time it takes to integrate data in SQL Server with existing systems. In addition, native Web service support is built into SQL Server to ensure interoperability with other applications and platforms.

· Development tools: SQL Server offers integrated development tools for the database engine, data extraction, transformation, and loading (ETL), data mining, OLAP, and reporting that are tightly integrated with Microsoft Visual Studio® to provide end-to-end application development capabilities. Every major subsystem in SQL Server ships with it’s own object model and set of APIs to extend the data system in any direction that is unique to your business.

The SQL Server 2005 data platform provides organizations of all sizes with the following benefits:

· Leverage data assets: In addition to delivering a secure, reliable database for line-of-business and analytical applications, SQL Server 2005 enables customers to get more value from their data by including embedded functionality such as reporting, analysis, and data mining.

· Increase productivity: Through comprehensive business intelligence capabilities and integration with familiar tools such as the Microsoft Office System, SQL Server 2005 provides information workers across your organization with critical, timely business information that is tailored to their specific needs. The goal is to extend BI to all users within an organization and ultimately to allow users at all levels of the organization to make better business decisions based on one of their most valuable assets—their data.

· Reduce Information Technology complexity: SQL Server 2005 simplifies the development, deployment, and management of line-of-business and analytical applications by providing a flexible development environment for developers and integrated, automated management tools for database administrators.

· Lower total cost of ownership (TCO): The integrated approach and focus on ease-of-use and deployment provides the industry’s lowest upfront, implementation, and maintenance costs for rapid return on your database investment.

What’s New in SQL Server 2005

Enterprise Data Management

In today’s connected world, data and the systems that manage that data must always be secure yet available to your users. With SQL Server 2005, users and Information Technology professionals across your organization will benefit from reduced application downtime, increased scalability and performance, and tight yet flexible security controls. SQL Server 2005 also includes many new and improved capabilities to help make your Information Technology staff more productive. SQL Server 2005 includes key enhancements to enterprise data management in the following areas:

· Manageability

· Availability

· Scalability

· Security

Manageability

SQL Server 2005 makes it simpler and easier to deploy, manage, and optimize enterprise data and analytical applications. As an enterprise data management platform, it provides a single management console that enables data administrators anywhere in your organization to monitor, manage, and tune all of the databases and associated services across your enterprise. It provides an extensible management infrastructure that can be easily programmed using SQL Management Objects (SMO), enabling users to customize and extend their management environment and Independent Software Vendors (ISVs) to build additional tools and functionality to further extend the capabilities that come out of the box.

SQL Server Management Studio

SQL Server 2005 simplifies management by providing one integrated management console to monitor and manage the SQL Server relational database, as well as Integration Services, Analysis Services, Reporting Services, Notification Services, and SQL Mobile across large numbers of distributed servers and databases. Database administrators can perform several tasks at the same time including: authoring and executing a query, viewing server objects, managing an object, monitoring system activity, and viewing online help. SQL Server Management Studio hosts a development environment for authoring, editing and managing scripts and stored procedures using Transact-SQL, Multidimensional Expressions (MDX), XMLA, and SQL Server Mobile Edition. Management Studio is readily integrated with source control. Management Studio also hosts tools for scheduling SQL Server Agent jobs and managing maintenance plans to automate daily maintenance and operation tasks. The integration of management and authoring in a single tool coupled with the ability to manage all types of servers provides enhanced productivity for database administrators.

Proactive Performance Monitoring and Performance Tuning

SQL Server 2005 exposes more than 70 new measures of internal database performance and resource usage from memory, locking, and scheduling to transactions and network and disk I/O. These Dynamic Management Views (DMVs) provide greater transparency and visibility into the database and a powerful infrastructure for proactive monitoring of database health and performance.

SQL Management Objects

SQL Management Objects (SMO) is a new set of programming objects that exposes all of the management functionality of the SQL Server database. In fact, Management Studio was built with SQL Management Objects. SMO is implemented as a Microsoft .NET Framework assembly. You can use SMO to automate common SQL Server administrative tasks, such as programmatically retrieving configuration settings, creating new databases, applying Transact-SQL scripts, creating SQL Server Agent jobs, and scheduling backups. The SMO object model is a more secure, reliable, and scalable replacement for Distributed Management Objects (DMO), which was included with earlier versions of SQL Server.

Availability

Investments in high availability technologies, additional backup and restore capabilities, and replication enhancements will enable enterprises to build and deploy highly available applications. Innovative high availability features such as; database mirroring, failover clustering, database snapshots, and enhanced online operations will minimize downtime and help to ensure that critical enterprise systems remain accessible. We will review these enhancements in greater detail in this section.

Database Mirroring

Database mirroring allows continuous streaming of the transaction log from a source server to a single destination server. In the event of a failure of the primary system, applications can immediately reconnect to the database on the secondary server. The secondary instance detects failure of the primary server within seconds and accepts database connections immediately. Database mirroring works on standard server hardware and requires no special storage or controllers. Figure 2 shows the basic configuration of database mirroring.

Figure 2: Basic Configuration of Database Mirroring

Failover Clustering

Failover clustering is a high availability solution that exploits Microsoft Windows® Clustering Services to create fault-tolerant virtual servers that provide fast failover in the event of a database server failure. In SQL Server 2005, support for failover clustering has been extended to SQL Server Analysis Services, Notification Services, and SQL Server replication. The maximum number of cluster nodes has been increased to eight. SQL Server failover clustering is now a complete fault-tolerant server solution.

Availability Feature	Database Mirroring	Failover Clustering
Automatic Failover	Yes	Yes
Transparent Client Redirection	Yes, auto-redirect	Yes, reconnect to same IP
Impact on Overall Throughput	No impact to minimal	No impact
Zero Work Loss	Yes	Yes
Requires Certified Hardware	No	Yes
Provides Redundant Data	Yes	No

Database Snapshots

SQL Server 2005 introduces the ability for database administrators to create instant, read-only views of a database. The database snapshot provides a stable view without the time or storage overhead of creating a complete copy of the database. As the primary database diverges from the snapshot, the snapshot adds its own copy of pages as they are modified. Thus the snapshot may be used to quickly recover from an accidental change to a database by simply reapplying the original pages from the snapshot to the primary database.

Fast Recovery

SQL Server 2005 improves the availability of SQL Server databases with a new faster recovery option. Users can reconnect to a recovering database after the transaction log has been rolled forward. Earlier versions of SQL Server required users to wait until incomplete transactions had rolled back, even if the users did not need to access the affected parts of the database.

Dedicated Administrator Connection

SQL Server 2005 introduces a dedicated administrator connection to access a running server even if the server is not responding or is otherwise unavailable. This allows you to execute diagnostic functions or Transact-SQL statements in order to troubleshoot problems on a server. The connection is activated by members of the sysadmin fixed server role and is only available through the SQLCMD command prompt utility either locally, or from a remote machine.

Online Operations (index operations and restore)

The ability to create, rebuild, or drop an index online is an enhanced feature of SQL Server 2005 that augments the indexing capabilities of earlier versions of SQL Server. The online index option allows concurrent modifications (updates, deletes, and inserts) to the underlying table or clustered index data and any associated indexes during index data definition language (DDL) execution. With support for online index operations, you can add indexes without interfering with access to tables or other existing indexes. Additionally, the server workload allows index operations to take advantage of parallel processing

SQL Server 2005 also introduces the ability to perform a restore operation while an instance of SQL Server is running. Online restoration capabilities improve the availability of SQL Server because only the data that is being restored is unavailable. The rest of the database remains online and available. Earlier versions of SQL Server require that you bring a database offline before you restore the database.

Replication

Replication is designed to increase data availability by distributing the data across multiple database servers. Availability is increased by allowing applications to scale out the SQL Server read workload across databases. SQL Server 2005 offers enhanced replication using a new peer-to-peer model that provides a new topology in which databases can be synchronized transactionally with any identical peer database.

Scalability

Scalability advancements such as table partitioning, snapshot isolation, and 64-bit support will enable you to build and deploy your most demanding applications using SQL Server 2005. The partitioning of large tables and indexes significantly enhances query performance against very large databases.

Table and Index Partitioning

Table and index partitioning eases the management of large databases by facilitating the management of the database in smaller, more manageable chunks. While the concept of partitioning data across tables, databases, and servers is not new to the world of databases, SQL Server 2005 provides a new capability for the partitioning of tables across filegroups in a database. Horizontal partitioning allows for the division of a table into smaller groupings based on a partitioning scheme. Table partitioning is designed for very large databases, from hundreds of gigabytes to terabytes and beyond.

Snapshot Isolation

Once data is copied, transformed, and archived to an analysis-oriented database it must be maintained and/or rebuilt periodically. Users certainly benefit from looking at a transactionally consistent version of the database; however, the version of the data that they are viewing is no longer current. It can take many hours to build and index the and that might not be what the user really needs. This is where snapshot isolation comes in. The snapshot isolation level allows users to access the last row that was committed, by using a transactionally consistent view of the database. This new isolation level provides the following benefits:

· Increased data availability for read-only applications.

· Nonblocking read operations allowed in an OLTP environment.

· Automatic mandatory conflict detection for write transactions.

· Simplified migration of applications from Oracle to SQL Server.

Replication Monitor

Replication Monitor is a tool that sets a new standard for ease of use in managing complex data replication operations with its intuitive user interface and wealth of data metrics.

Support for 64-Bit System Itanium2 and x64

Optimized for the Intel Itanium processor, SQL Server (64-bit) takes advantage of advanced memory addressing capabilities for essential resources such as buffer pools, caches, and sort heaps, reducing the need to perform multiple I/O operations to bring data in and out of memory from disk. Greater processing capacity without the penalties of I/O latency opens the door to new levels of application scalability.

Windows Server™ 2003 x64 provides high performance for both 32-bit and 64-bit applications on the same system. The underlying architecture is based on 64-bit extensions to the industry-standard x86 instruction set, allowing today's 32-bit applications to run natively on x64 processors. At the same time, new 64-bit applications are executed in 64-bit mode, which processes more data per clock cycle, allows greater access to memory, and speeds numeric calculations. The end result is a platform that leverages the existing wealth of 32-bit applications while also providing a smooth migration path to 64-bit computing.

Security

SQL Server 2005 makes significant enhancements to the security model of the database platform, with the intention of providing more precise and flexible control to enable tighter security of the data. A considerable investment has been made in a number of features to provide a high level of security for your enterprise data including:

· Enforcing policies for SQL Server login passwords in the authentication space.

· Providing for more granularity in terms of specifying permissions at various scopes in the authorization space.

· Allowing for the separation of owners and schemas in the security management space.

Authorization

A new security model in SQL Server 2005 allows administrators to manage permissions at a granular level and at a designated scope, making management of permissions easier as well as ensuring that the principle of least privileges is upheld. SQL Server 2005 allows you to specify a context under which statements in a module execute. This feature also acts as an excellent mechanism for granular permission management.

Authentication

SQL Server 2005 clustering supports Kerberos authentication against a SQL Server 2005 virtual server. Administrators can specify Microsoft Windows-style policies on standard logins so that a consistent policy is applied across all accounts in the domain.

Native Encryption

SQL Server 2005 supports encryption capabilities within the database itself, fully integrated with a key management infrastructure. By default, client/server communications are encrypted. To centralize security assurance, server policy can be defined to reject unencrypted communications.

SQL and Trustworthy Computing

The Trustworthy Computing initiative outlines a framework that defines the steps necessary to support secure computing as well as measures that help you deploy and maintain a secure environment. These steps help to protect the confidentiality, integrity, and availability of data and systems at every phase of the software life cycle—from design, to delivery, to maintenance. To uphold the four tenets of the Trustworthy Computing initiative, Microsoft and the SQL Server team have taken the following steps:

· Secure by design. The SQL Server development team conducted multiple security audits and spent more than two months studying SQL Server components and the interaction between them. For each potential security threat, the team did a threat analysis to evaluate the issue and completed additional design and testing work to neutralize potential security issues. As a result of these design efforts, SQL Server 2005 includes many new server security features.

· Secure by default. Upon installation, SQL Server 2005 chooses the right set of configuration values for all setup options, ensuring that when a new system is installed, it will be in a secure state by default.

· Secure in deployment. Microsoft has created content to help organizations deploy SQL Server using the proper security credentials and to fully understand the steps and permissions required. SQL Server deployment tools provide the information necessary to understand the decisions you need to make during deployment. Security updates are easy to find and install—and if you choose the option, the updates install automatically. Tools are also available to help you assess and manage security risks across organizations.

Developer Productivity

SQL Server 2005 includes many new technologies that bring significant increases in developer productivity. From .NET Framework support to tight integration with Visual Studio®, these features provide developers with the ability to more easily create secure, robust database applications at a lower cost. SQL Server 2005 enables developers to leverage existing skills across a variety of development languages while providing an end-to-end development environment for the database. Native XML capabilities will also allow developers to build new classes of connected applications across any platform or device.

Enhancements for developer productivity include:

· Expanded language support

· Improved development tools

· Extensibility

· Improved data access

· XML and Web services

· Application Framework

Expanded Language Support

Because the common language runtime (CLR) is hosted in the database engine, developers can choose from a variety of familiar languages to develop database applications, including Transact-SQL, Microsoft Visual Basic® .NET, and Microsoft Visual C#® .NET. Additionally, CLR hosting will provide developers with increased flexibility through the use of user-defined types and functions. The CLR will also provide opportunities to use third-party code for rapid database application development.

CLR/.NET Framework integration

With the release of Microsoft SQL Server 2005, database programmers can now take full advantage of the Microsoft .NET Framework class library and modern programming languages to implement functionality within the server. Using common language runtime (CLR) integration, you can code your stored procedures, functions, and triggers in the .NET Framework language of your choice. Microsoft Visual Basic .NET and the C# programming language both offer object-oriented constructs, structured exception handling, arrays, namespaces, and classes. In addition, the .NET Framework provides thousands of classes and methods that have extensive built-in capabilities that you can easily use on the server-side. Many tasks that were awkward or difficult to perform in Transact-SQL can be better accomplished by using managed code; additionally, two new types of database objects—aggregates and user-defined types—are available. You can now better use the knowledge and skills that you have already acquired to write in-process code. In short, SQL Server 2005 enables you to extend the database server to more easily perform appropriate computation and operations on the back end.

This integration between SQL Server and the CLR provides several major benefits:

· Enhanced programming model: Programming languages that are compatible with the .NET Framework are in many respects richer than Transact-SQL, offering constructs and capabilities that were previously not available to SQL developers.

· Enhanced safety and security: Managed code runs in a CLR environment, hosted by the database engine. This allows .NET Framework database objects to be safer and more secure than the extended stored procedures available in earlier versions of SQL Server.

· User-defined types and aggregates: Two new database objects that expand the storage and querying capabilities of SQL Server are enabled by hosting the CLR.

· Common development environment: Database development is integrated into the Microsoft Visual Studio 2005 development environment. You can use the same tools for developing and debugging database objects and scripts that you use to write middle-tier or client-tier .NET Framework components and services.

· Performance and scalability: Because managed code compiles to native code prior to execution, you can achieve significant performance increases in some scenarios.

By using languages such as Visual Basic .NET and C#, you can capitalize on CLR integration to write code that has more complex logic and is more suited for computation tasks. In addition, Visual Basic .NET and C# offer object-oriented capabilities such as encapsulation, inheritance, and polymorphism. You can easily organize related code into classes and namespaces, which means that you can more easily organize and maintain your code investments when you are working with large amounts of code. The ability to logically and physically organize code into assemblies and namespaces is a huge benefit, that allows you to better find and relate different pieces of code in a large database implementation.

Managed code is more efficient than Transact-SQL at processing numbers and managing complicated execution logic, and provides extensive support for string handling, regular expressions, and so on. Also, with the functionality that is available in the .NET Framework class library, you have full access to thousands of pre-built classes and routines that you can access easily from any stored procedure, trigger, or user-defined function. Everything from improved string-handling functions, math functions, date operations, access to system resources, advanced encryption algorithms, file access, image processing, and XML data manipulation is easily accessible from managed stored procedures, functions, triggers, and aggregates.

One of the major benefits of managed code is type safety. Before managed code is executed, the CLR performs several checks through a process known as verification to ensure that the code is safe to run. For example, the code is checked to ensure that memory is not read that has not been written to.

Transact-SQL enhancements

Transact-SQL has long been the basis for all programmability of SQL Server. SQL Server 2005 provides many new language capabilities for developing scalable database applications. These enhancements include error handling, new recursive query capabilities, and support for new SQL Server Database Engine capabilities. Transact-SQL enhancements in SQL Server 2005 increase your expressive powers in query writing, allowing you to improve the performance of your code and extend your error management capabilities. The continuous effort that is being put into enhancing Transact-SQL shows a firm belief in its significant role in SQL Server.

Improved Development Tools

Developers will be able to use one development tool for Transact-SQL, XML, Multidimensional Expressions (MDX), and XML for Analysis (XML/A). Integration with the Visual Studio development environment will provide more efficient development and debugging of line-of-business and business intelligence (BI) applications.

Business Intelligence Development Studio

The Business Intelligence Development Studio is a common development environment for building BI solutions based on Visual Studio including a database engine, analysis services, and reporting services. Use the Business Intelligence Development Studio graphical user interface to design SQL Server Integration Services (SSIS) packages for data management applications. SSIS packages are designed, developed, and debugged in the Business Intelligence Development Studio by dragging tasks from the toolbox, setting their properties, and connecting tasks with precedence constraints. Figure 3 shows the interface in Visual Studio for the Business Intelligence Development Studio.

Figure 3: Business Intelligence Development Studio interface in Visual Studio

Visual Studio Integration

SQL Server 2005 and Visual Studio 2005 together provide deeper levels of integration between the database and the application development environment than ever before. Developers now have the ability to create CLR stored procedures, functions, user-defined types, and user-defined aggregates directly from within the Visual Studio development environment. They can deploy these new database objects directly from Visual Studio without having to switch tools. Visual Studio 2005 supports all of the new SQL Server data types, such as native XML directly. You can also add your CLR database objects to the same source control system that you use for all you Visual Studio projects, thus providing an even greater level of integration and security to your development processes.

Cross-Tier and Cross-Language Debugging

SQL Server 2005 and Visual Studio 2005 together provide even deeper integration in the area of application debugging. The combination allows you to seamlessly debug both CLR and Transact-SQL code using the same Visual Studio debugging interface and it allows you to debug from CLR to Transact-SQL and back again, regardless of the location of the code, whether it is on the developer machine or stored in the SQL Server database.

Extensibility

User-Defined Types and Aggregates

User-defined types in SQL Server 2005 are not an object relational extensibility mechanism. They are a way to extend the scalar type system of the database. The scalar type system includes the columnar types that ship with SQL Server (types like int, nvarchar, uniqueidentifier, etc.). With user-defined types, you can define your own type that can be used for column definitions, for example. Create a user-defined type if your type really is an atomic value that is appropriate to be modeled as a column.

Use user-defined types if you need to define your own scalar type. Example scenarios for such types include custom date/time data types in various calendars, and currency data types. With user-defined types, you can create a single object that exposes all the behaviors that are available on the type, and encapsulate, or hide, the underlying data that is stored by the type. Everyone that needs to access the data has to use the user defined type programmatic interface. If you can leverage existing functionality in the .NET Framework (such as the internationalization or calendar functionality), that is another really good reason to consider implementing your type as a user-defined type.

There are a number of scenarios where you may need to perform aggregations over data. This includes performing statistical calculations, such as avg, stddev, etc. If the desired aggregation function is not directly supported as a built-in aggregate function, there are three ways to perform a custom aggregation in SQL Server 2005:

· Write the aggregation as a user-defined aggregate.

· Write the aggregate using a CLR stored procedure.

· Use a server-side cursor.

SQL Management Objects(SMO)

SQL Management Objects (SMO) is the management object model for SQL Server 2005. SMO represents significant design and architectural improvements for the SQL Server management object model. It is a simple to use but rich object model that is based on .NET Framework managed code. SMO is the primary tool for developing database management applications using .NET Framework. SMO is used by every dialog box in SQL Server Management Studio, and every administrative action that you can perform in SQL Server Management Studio you can also accomplish by using SMO.

The new SMO object model and the Microsoft Windows Management Instrumentation (WMI) APIs replace SQL-DMO. Where possible, SMO incorporates similar objects as SQL-DMO for ease of use. You can still use SQL Server 2005 with SQL-DMO, but SQL-DMO will not be updated to manage features that are specific to SQL Server 2005.

Analysis Management Objects

Analysis Management Objects (AMO) allows client applications to access the range of administrative commands and capabilities available to Analysis Services using an object library that can provide object-level validation capabilities, instead of having to manually generate DDL scripts for Analysis Services commands and the often-lengthy contents of the Analysis Services Scripting Language (ASSL) ObjectDefinition element. Applications using AMO can either connect and work directly with objects on an Analysis Services instance, or create such objects without an existing connection and persist the metadata for later deployment. AMO also “wraps” ASSL commands and elements.

Improved Data Access and Web Services

In SQL Server 2005, you can develop XML Web services in the database tier, making SQL Server an HTTP listener. This provides a new type of data access capability for applications that are centralized around Web services. In SQL Server 2005 you can use HTTP to access SQL Server directly, without using a middle-tier listener such as Microsoft Internet Information Services (IIS). SQL Server exposes a Web service interface, to allow the execution of SQL statements and invocation of functions and procedures. Query results are returned in XML format and can take advantage of the Web services infrastructure of Visual Studio.

ADO.NET 2.0/ADOMD.NET

There is much that's new in the next version of ADO.NET. From new support for query change notifications, to Multiple Active Result Sets (MARS), ADO.NET evolves dataset access and manipulation to achieve greater scalability and flexibility.

Query notification

SQL Server 2005 introduces notification support for SQL Server queries. You can use this support to send a command to SQL Server and to request that a notification be generated if executing the same command again produces different results from those obtained initially. You accomplish this by using a dependency object that detects when the underlying data is changed. Commands that are sent to the server through any of the client APIs such as ADO.NET, OLE DB, Open Database Connectivity (ODBC), Microsoft ActiveX® Data Objects (ADO), or SOAP may include a tag that requires a notification. For each statement that is executed as part of the request, the server creates a notification subscription that fires once for each statement that is included in the request. Notifications are delivered through a SQL Service Broker queue that applications can poll, and use activation services or blocking statements that return whenever the notifications are available. Query notifications are useful for enabling the caching of results in applications such as database-driven Web sites. Figure 4 shows the query notification process.

Figure 4: Query notification

MARS

MARS provides the ability to have more than one pending request per connection, in particular to have more than one default result set open per connection. Default result sets are forward-only read-only result sets. For default result sets, the client drivers transparently retrieve the data in large chunks (Tabular Data Stream buffer sized chunks) so that application requests are satisfied without a roundtrip to the server (as in the case of server cursors). The application can use a simple row-at-a-time programming model without compromising performance. The multiple active result sets feature removes the current restriction in which an open default result set blocks the driver from sending requests to the server until the entire result set is consumed.

Transparent failover for data mirroring

SQL Server 2005 supports a "hot spare" capability through database mirroring. If a SQL Server instance fails, the work can be shifted over to the backup server automatically. This requires an instance to witness the failover known as (not surprisingly) the witness instance. Hot spare scenarios require that existing client connections must "know" to fail over (establish a connection with the new server instance), as well. Client connections that produce an error on the next attempted access and must be manually "failed over" by client programming are suboptimal. SqlClient in ADO.NET 2.0 supports client failover without special programming of the application program.

XML Support

Advancements such as native XML data type and XQuery help organizations to seamlessly connect internal and external systems. SQL Server 2005 will support both relational and XML data natively, so enterprises can store, manage, and analyze data in the format that best suits their needs. Support for existing and emerging open standards such as Hypertext Transfer Protocol (HTTP), XML, Simple Object Access Protocol (SOAP), XQuery, and XML Schema definition language (XSD) will also facilitate communication across extended enterprise systems.

XML Data Type

XML can model complex data; it is not limited to the scalar types that are supported by SQL Server. As such, a string-based, built-in data type such as char or varchar does not suffice to make full and effective use of the power and the numerous advantages of XML. For example, if XML is stored as a string, you can insert or select an entire document, or even retrieve contiguous bytes from it, but you cannot query into the contents of the document itself. By providing the XML data type, SQL Server 2005 allows you to query portions of an XML document, validate that the document conforms to an XML schema, and even modify the contents of the XML document in place. It also integrates traditional, relational data with data in unstructured or semi-structured XML documents in ways that are not possible with SQL Server 2000. In SQL Server 2005, XML data is stored as binary large objects (BLOBs) in an internal representation that allows efficient reparsing and some compression.

A collection of XML schemas can be associated with a column of type XML. This provides validation for constraints, inserts, and updates, and typing of values inside stored XML data, as well as optimizations for storage and query processing. SQL Server 2005 also provides several DDL statements for managing schemas on the server.

XQuery

The XML Query Language, or XQuery, is an intelligent and robust language that is optimized for querying all types of XML data. With XQuery you can run queries against variables and columns of the XML data type using the latter's associated methods. As with many of the XML standards, the World Wide Web Consortium (W3C) oversees the development of XQuery. XQuery evolved from a query language called Quilt, which was itself based on a variety of other query languages such as the XML Path Language (XPath) version 1.0, XQL, and SQL. It also contains XPath 2.0 as a subset. Therefore, if you have experience using XPath 1.0, you can capitalize on your skills and do not have to learn an entirely new query language. There are, however, significant enhancements that go beyond XPath 1.0, such as typing, special functions, and support for better iteration, sorting of results, and construction.

SQL Server 2005 ships with deep XQuery capabilities that allow for XML object manipulation in the data tier. It supports a statically typed subset of the XQuery 1.0 Working Draft of November 15, 2003.

Web Services Support

In SQL Server 2005, you can develop XML Web services in the database tier, making SQL Server an HTTP listener. This provides a new type of data access capability for applications that are centralized around Web services. In SQL Server 2005, you can use HTTP to access SQL Server directly without using a middle-tier listener such as Microsoft Internet Information Services (IIS). SQL Server exposes a Web service interface to allow the execution of SQL statements and invocation of functions and procedures. Query results are returned in XML format and can take advantage of the Web services infrastructure of Visual Studio.

XML for Analysis Services (XML/A)

XML for Analysis Services (XML/A) is the native, standards-based protocol for communicating with the Analysis Services server. New kinds of applications are enabled and easy to develop—applications that integrate analytics with operations in real time. With XML/A as the native protocol, Analysis Services clients can be configured to have a zero footprint, and each server is automatically a Web service. A light-footprint Win32 layer is available for backward compatibility with tools that work with Analysis Services 2000 on OLE DB for OLAP, ADOMD, and ADOMD.NET. Many users will continue to use the ADOMD.NET object model to build custom applications on Analysis Services.

Application Framework

SQL Server 2005 introduces a new SQL Server application framework including: Service Broker, Notification Services, SQL Server Mobile, and SQL Server Express. Service Broker is a distributed application framework that provides reliable asynchronous messaging at the database to database level.

Service Broker

Over the last 10 years, the proliferation of e-commerce applications has created the need for increased workflow management across database applications. When an online customer places an order for a book, this order needs to commit transactions into the inventory, shipping, and credit card systems, and also needs to send an order confirmation using another Web application. Waiting for each of these processes to happen in order doesn't scale well. SQL Server 2005 provides a new scalable architecture for building asynchronous message routing. Figure 5 outlines the Service Broker architecture.

Figure 5: Service Broker architecture

The Service Broker technology allows internal or external processes to send and receive streams of reliable, asynchronous messages by using extensions to normal Transact-SQL data manipulation language. Messages are sent to a queue in the same database as the sender, to another database in the same instance of SQL Server, or to another instance of SQL Server either on the same server or on a remote server.

Notification Services

Microsoft SQL Server Notification Services is a platform for developing and deploying applications that generate and send notifications to users. Notifications are personalized, timely messages that can be sent to a wide variety of devices.

Notifications reflect the preferences of the subscriber. The subscriber enters a subscription to express an interest in information. For example, "notify me when the stock price of Adventure Works reaches $70.00," or "notify me when the strategy document my team is writing is updated."

A notification can be generated and sent to the user as soon as a triggering event occurs, or it can be generated and sent on a predetermined schedule that the user specifies. The user's subscription specifies when the notification should be generated and sent.

Notifications can be sent to a wide variety of devices. For example, a notification can be sent to a user's mobile phone, personal digital assistant (PDA), Microsoft Windows Messenger, or e-mail account. Because these devices often accompany the user, notifications are ideal for sending high-priority information.

SQL Server Mobile Edition

SQL Server 2000 shipped with SQL Server 2000 Windows CE Edition, which is now SQL Server Mobile Edition version 3.0. There are a number of new key features in SQL Server Mobile Edition that relate to developers:

· You can create a SQL Server Mobile Edition database on the desktop or on the device, directly from SQL Server Management Studio. You can also manipulate the schema of the SQL Server Mobile Edition database directly from Management Studio, regardless of whether the database resides on the mobile device or on the desktop. You can use SQL Server Management Studio to run queries that target a SQL Server Mobile Edition database on the device or on the desktop. You can also take advantage of new SQL Server Mobile Edition features that include an XML showplan rendered in a GUI format just like native SQL Server and the ability to use query hints to override the query optimizer in SQL Server Mobile Edition. For the first time, you can control the optimization plan on a device.

· You can now code against SQL Server Integration Services (SSIS) objects to exchange data.

· The new SqlCeResult set is derived from the SQLResult set that is in SQL Server 2005. This allows SQL Server Mobile Edition to have a true scrollable, updateable cursor. It also allows binding to data objects that are on devices.

· You can code an application to synchronize data while leaving the main application open, and you can have two separate applications access the same database on the device at the same time.

· You can get notifications that you can code into status bars that will give the status of a synchronization. Previously, there was no way to know how far synchronization status was, to notify users that a device had not stopped responding.

· You can maintain the small size of the database through a much more aggressive page reclamation policy.

· You can share parameterized query code with SQL Server syntax.

SQL Server Express

More than ever developers are leveraging relational databases to provide a rich end-user experience. Protecting and managing information inside these applications is critical. Microsoft SQL Server Express helps developers build robust and reliable applications by providing a free, easy to use, and robust database. Too often database systems are overly complex for building simple applications. Microsoft Visual Studio 2005 and SQL Server Express reduce this complexity by providing a simple but powerful development environment for building data-driven applications. Developers can design schemas, add data, and query local databases, all inside the Visual Studio 2005 environment. If developers need more advanced database features, then SQL Server Express can be seamlessly upgraded to more sophisticated versions of SQL Server. Figure 6 shows the Query Editor interface in SQL Server Express Manager

Figure 6: The Query Editor in SQL Server Express Manager (XM)

A new GUI tool called SQL Server Express Manager (XM) is freely available as a separate Web download. XM allows easy database management and query analysis capabilities, will have a small download size, and will be freely redistributable. XM supports connections to SQL Server Express and other SQL Server 2005 editions, SQL Server 2000, and MSDE 2000. A simplified connection dialog box guides the user through the selection of the instance and the authentication methods to be used. Both local and remote connections are possible using XM. Object Explorer will enumerate and display the common objects used, such as the instance, tables, stored process, etc., in a hierarchical manner and will help the user visualize access to the database.

All database management functionalities are available by invoking the right-click context menu from Object Explorer. Some of the database management options to be exposed include creating and modifying databases, tables, logins, and users. Many of these common database operations are available as task wizards that guide the user through the process, while many others are available as tabbed window documents. For instance, XM will provide a New/Edit Database document for creating new databases and editing existing databases.

Many database users prefer to manage their servers using Transact-SQL, since this approach offers finer-grained control than using the graphical user interface. The Query Editor in XM will allow users to develop and execute Transact-SQL statements and scripts. The Query Editor will have rich features such as keyword color-coding and a results pane that returns results in a data grid. The error messages, if any, will also be shown in the results pane.

Business Intelligence

SQL Server 2005 will further Microsoft’s leadership in the are of business intelligence (BI) through innovations in scalability, data integration, development tools, and rich analytics. SQL Server 2005 enables scalable business intelligence by putting critical, timely information in the hands of employees across your organization. From the CEO to the information worker, employees will be able to quickly and easily harness data to make better decisions faster. The comprehensive integration, analysis, and reporting capabilities of SQL Server 2005 enable companies to extend the value of their existing applications, regardless of the underlying platform.

Business intelligence features include enhancements in the following areas:

· End-to-end integrated business intelligence platform

· Integration Services

· Analysis Services

· Reporting Services

· Integration with the Microsoft Office System

End-to-End Integrated Business Intelligence Platform

SQL Server 2005 is a complete business intelligence platform that provides the features, tools, and functionality to build both classic and innovative kinds of analytical applications. The following provides an introduction to the tools that you will use to build an analytical application, and highlights new functionality that makes it easier than ever to build and manage complex BI systems.

The SQL Server 2005 business intelligence toolset delivers end-to-end BI application integration:

· Design: Business Intelligence Development Studio is the first integrated development environment designed for the business intelligence developer. Built on Visual Studio 2005, the Business Intelligence Development Studio delivers a rich, integrated, professional development platform for BI system developers. Debugging, source control, and script and code development are available for all components of the BI platform.

· Integrate: SQL Server Integration Services (SSIS) has been rewritten to perform complex data integration, transformation, and synthesis at high speed for very large data volumes. The Business Intelligence Development Studio makes building and debugging packages positively fun. Integration Services, Analysis Services, and Reporting Services work together to present a seamless view of data from heterogeneous sources.

· Analyze: Microsoft Data Mining has always been easy to use. Now it's even better with the addition of important new algorithms, including Association Rules, Time Series, Regression Trees, Sequence Clustering, Neural Network, and Naïve Bayes. SQL Server 2005 blurs the lines between relational and multidimensional databases. You can store data in the relational database, in the multidimensional database, or use the new Proactive Cache feature to get the best of both worlds. Important new analytical capabilities have been added to Analysis Services cubes as well: these include Key Performance Indicator (KPI) framework, MDX scripts, and other built-in advanced business analytics. The Reporting Services report delivery and management framework enables easy distribution of complex analytics to the widest possible audience.

· Report: Reporting Services extends the Microsoft business intelligence platform to reach the business user who needs to consume the analysis. Reporting Services is an enterprise managed reporting environment, embedded and managed via Web services. Reports can be personalized and delivered in a variety of formats, with a range of interactivity and printing options. Complex analyses can reach a broad audience through the distribution of reports as a data source for downstream business intelligence. New with SQL Server 2005 is the reporting tool, Report Builder.

· Manage: SQL Server Management Studio integrates the management of all SQL Server 2005 components. Business intelligence practitioners will benefit from Microsoft's extension of the server abilities you expect from the relational engine—scalability, reliability, availability, programmability, and so on—to the full set of BI platform components.

Integration Services

SQL Server 2005 includes a redesigned enterprise ETL platform, called SQL Server Integration Services (SSIS). SQL Server Integration Services enables organizations to more easily integrate and analyze data from multiple heterogeneous information sources. By analyzing data across a wide array of operational systems, organizations may gain a competitive edge through a holistic understanding of their business.

Enterprise ETL Platform

This new platform is the successor to the popular feature in SQL Server 2000, called Data Transformation Services (DTS). SSIS is completely new for SQL Server 2005. SSIS provides the breadth of features, and very high scale performance that is necessary to build enterprise-class ETL applications. SSIS is fully programmable, embeddable, and extensible—characteristics that make it an ideal ETL platform.

Beyond Traditional ETL

SQL Server 2005 supports nontraditional data (Web Services, XML) out-of-the box through:

· SSIS brings analytics to the data without persisting the data.

· Data Mining and text mining in the data flow.

· Data Mining and analytics are brought to the data flow for data quality and data cleansing.

Analysis Services

With SQL Server 2005, Analysis Services provides, for the first time, a unified and integrated view of all your business data as the foundation for all of your traditional reporting, OLAP analysis, and data mining.

Unified Dimensional Model

By combining the best aspects of traditional OLAP analysis and relational reporting, Analysis Services 2005 provides a metadata model that covers both sets of needs. A set of cubes and dimensions defined in Analysis Services 2005 is referred to as a Unified Dimensional Model (UDM). The UDM is a central metadata repository defining business entities, business logic, calculations, and metrics that serves as the source for all reports, spreadsheets, OLAP browsers, KPIs, and analytical applications.

Using the powerful new Data Source View feature, the UDM is mapped to a host of heterogeneous back-end data sources allowing a complete and integrated picture of the business regardless of the location of the data.

With the UDM’s friendly descriptions of the business entities, navigation hierarchies, multiple perspectives, and even automatic translations to native languages, users will find it easy to explore the corporate business data.

Data Mining

Microsoft SQL Server 2005 Data Mining is the business intelligence technology that helps you build complex analytical models, and integrate those models with your business operations. Microsoft SQL Server 2005 Analysis Services establishes new ground for data mining. By creating an easy to use, extensible, accessible, and flexible platform, SQL Server 2005 Analysis Services data mining capabilities introduces data mining to organizations that previously would never have considered a data mining solution.

Through an enterprise class architecture; a deep integration with the SQL Server family of business intelligence tools, and a rich set of tools, APIs and algorithms, SQL Server enables the creation of a new breed of intelligent applications that enhance productivity, increase profits and reduce costs by providing customized data-driven solutions to a broad range of business problems.

Reporting Services

Reporting Services extends the Microsoft BI platform to reach the information worker who needs access to business data. Reporting Services is a server-based enterprise reporting environment, managed via Web services. Reports can be delivered in a variety of formats, with a range of interactivity and printing options. Complex analyses can reach a broad audience through the distribution of reports as a data source for downstream business intelligence.

An integrated component of SQL Server 2005, Reporting Services provides:

· A high performance engine for processing and formatting reports.

· A complete set of tools for creating, managing, and viewing reports.

· An extensible architecture and open interfaces for embedding reports or integrating reporting solutions in diverse Information Technology environments.

Relational and OLAP Reports

Reports built on relational data are useful but the ability to add additional analytic capabilities makes reporting powerful. Reporting Services allows you to easily build reports together or separately. SQL Server 2005 supports both relational and OLAP data and provides a query editor for both including SQL Query Editor and MDX Query Editor.

Report Builder

Report Builder, a new component of SQL Server 2005 Reporting Services, allows business users to create their own reports using a user-friendly model of their data. Report Builder leverages the Reporting Services platform to bring ad hoc reporting to all end users. Users create and edit reports with the Report Builder client application. The Report Builder user interface is built on top of familiar Microsoft Office paradigms such as Excel and PowerPoint. Figure 7 shows a sample Report Builder report.

Figure 7: Design reports with Report Builder

Report Builder is a ClickOnce application deployed via the browser. Users start by selecting report layout templates containing predefined data sections such as tables, matrices and charts. They drag and drop report items from the model to the design surface and set constraints to filter the report data. The model contains all of the necessary information for the Report Builder to automatically generate the source query and retrieve the requested data. The Report Builder also allows users to:

· Add text and formatting to reports.

· Create new fields and calculations defined using the model.

· Preview, print, and publish reports.

· Export report data to formats such as Microsoft Excel.

Integration with the Microsoft Office System

Reports that are served up by the Report Server in Reporting Services can run in the context of Microsoft SharePoint® Portal Server and Microsoft Office System applications such as Microsoft Word and Microsoft Excel. You can use SharePoint features to subscribe to reports, create new versions of reports, and distribute reports. You can also open reports in Word or Excel to view HTML versions of the reports.

Upgrading to SQL Server 2005

Following are some tips for upgrading to SQL Server 2005.

· Upgrade to SQL Server 2005 from SQL Server 7.0 or SQL Server 2000.

· Run Upgrade Advisor before upgrading to determine if any product changes are expected to break existing applications.

· The Database Engine, Analysis Services, and Reporting Services can be upgraded by Setup.

· SQL Server Integration Services, the replacement for DTS, is installed side-by-side with DTS. You can run DTS packages using the DTS runtime components.

· SQL Server 2005 Notification Services is installed side-by-side with Notification Services 2.0. You must migrate instances of Notification Services to SQL Server 2005 when you upgrade the Database Engine.

· Use the Surface Area Configuration tool after upgrading to enable or disable SQL Server 2005 services, network protocols, and features.

Microsoft SQL Server Pricing and Licensing

The family of SQL Server editions includes everything you need in one product for a comprehensive, out-of-the-box data storage, management, analysis and reporting platform with flexible licensing that allows you to choose the solution that best fits your unique needs.

Designed to scale from the largest enterprise down to the smallest business, SQL Sever provides the same performance, security, reliability, and business value to all customers. SQL Server supports implementations ranging from multi-terabyte data warehouses to Pocket PC devices running SQL Server Windows CE Edition.

Pricing & licensing

Edition	Pricing	Benefit	Size	Key Features
Express	Free	Fastest way to learn, build and deploy simple data-driven applications.	1 CPU 1-GB RAM 4-GB DB size	Simple Management Tool Simple Reporting Replication & SSB Client
Workgroup	$3,900 per processor $739 (server + 5 users)	Most affordable and easiest to use database solution for smaller departments and growing businesses.	1-2 CPUs 3-GB RAM	Management Studio Import/Export Limited Replication Publishing Clustering Back-up Log Shipping
Standard	$6,000 per processor $2,799 (server + 10 users)	Complete data management and analysis platform for medium businesses and larger departments.	1-4 CPUs Unlimited RAM	Database Mirroring Basic ETL Standard OLAP Server with Analysis Services Standard Reporting with Reporting Services Data Mining Full Replication & SSB Publishing Available in native 32- and 64-bit editions Supports Itanium2 and x64
Enterprise	$25,000 per processor $13,500 (server + 25 users)	Fully integrated data management and analysis platform for business-critical enterprise applications.	Unlimited Scale & Partitioning	Advanced database mirroring, Complete online & parallel operations, and database snapshot. Advanced analysis tools including full OLAP & Data Mining. Advanced reporting with customized, high scale, and ad hoc reporting. Advanced ETL with complex data routing and transformation capabilities. Available in native 32 and 64 bit editions. Supports Itanium2 and x64

This table outlines the pricing and benefits for each edition of the Microsoft SQL Server 2005 product line.

Note Bold indicates a feature that is new for Microsoft SQL Server 2005. Each higher edition includes the same functionality as the edition below it. All prices are in US dollars and reflect pricing for purchases within the United States.

For more information on pricing and licensing and the SQL Server 2005 product line please visit the following:

http://www.microsoft.com/sql/howtobuy/default.asp

http://www.microsoft.com/sql/howtobuy/understdbpricing.asp

Windows Server System Common Engineering Roadmap

SQL Server is part of the Windows Server System—a comprehensive and integrated server infrastructure that simplifies the development, deployment, and operation of flexible business solutions.

As a key part of the Windows Server System family, SQL Server 2005 includes a standard set of capabilities such as common patch management, Watson support, and tools such as the Microsoft Baseline Security Analyzer to deliver a consistent and predictable experience to Windows Server System customers.

The goal of the Windows Server System Common Engineering Roadmap is to create a set of common services that will be implemented across all Windows Server System server products. This set of common services raises the bar for server infrastructure and helps ensure that products throughout Windows Server System are engineered for greater security, reliability, manageability, and flexibility. The Windows Server System Common Engineering Roadmap builds on the following initiatives to enable customers to meet today’s business challenges and the challenges of tomorrow.

To deliver on this vision of flexible Information Technology, Microsoft is currently focusing on three key initiatives:

· .NET, Microsoft’s Web services strategy, connects information, people, systems, and devices through software. Adopting services-oriented architecture throughout the Microsoft platform provides businesses with the ability to quickly build, deploy, manage, and use connected, security-enhanced systems based on Web services. These systems enable faster, more agile business integration and deliver on the promise of information anytime, anywhere, on any device.

· Dynamic Systems Initiative (DSI) is focused on delivering systems that are designed with operations in mind and are built to monitor ongoing operations and adjust dynamically based on models that can change with the business. This initiative unifies hardware, software, and service vendors around a model-based management that enables customers to harness the power of industry-standard hardware and brings simplicity, automation, and flexibility to Information Technology operations. The goal is to reduce management and operations costs, improve reliability, and increase responsiveness throughout the entire Information Technology life cycle.

· Trustworthy Computing is a long-term, company-wide, and collaborative effort to create and deliver more secure, private, and reliable computing experiences for users, while reducing the demands on users and Information Technology administrators. The goal of Trustworthy Computing is to deliver the security, privacy, reliability, and business integrity that people expect from the computing industry.

In the Common Engineering Criteria for 2005, 16 different specifications have been defined and applied throughout the Windows Server System. Beginning with 2005 versions, all Windows Server System products will either comply with these criteria, or have specific reasons for any exemptions, with implementation plans for future releases.

Microsoft will add specifications at regular intervals to continue to address customer requirements and deliver on the vision for Windows Server System. These specifications and their implementation details, including any exception information, will be published regularly on the Windows Server System Web site, http://www.microsoft.com/windowsserversystem.

VISION WORLD

Saturday, September 17, 2011

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