Identity

 Identity is a state or fact which distinguishes  one object  from another objects  , so identity column is one of the way of make rows  distinguishable in a table .

Decalring

                         IDENTITY  ( seed , increment ) 

Seed  : Is the value that is used for the very first row loaded into the table.

Increment : Is the incremental value that is added to the identity value of the previous row that was loaded.

CREATE TABLE employees

(

 id_num int IDENTITY(1,1),

 fname varchar (20),

 minit char(1),

 lname varchar(30)

)

DATA Insertion on Table

Sql server automatically takes care of incrementing and inserting this column value.

We can forcefully insert identity by running following

        SET IDENTITY_INSERT tablename off  

Important point

   Next identity column value will be the next value of the max value inserted on the column (if the value exists or not in the table)

 Ie