Identity in SQL SERVER 2012

IDENTITY:
It is used to generate unique values in sequential order.it can be called as autonumber.

If we use identity to a column there is no need of inserting values into that column. 
Syntax:

IDENTITY(<INITIAL_VALUE>/SEED,<INCREMENT>)

Example:

CREATE TABLE EMP1
(
ENO INT IDENTITY(1000,10),
ENAME VARCHAR(15)
)
Here we are specifying that eno is automatically generated when ever there is an insert is performed the eno starts with 1000 and increments with 10
INSERT INTO EMP1(ENAME) VALUES('RAMU')

SELECT * FROM EMP1

INSERT INTO EMP1(ENAME) VALUES('SRINIVAS')
INSERT INTO EMP1(ENAME) VALUES('ASHOK')
INSERT INTO EMP1(ENAME) VALUES('SURESH')

INSERT INTO EMP1(ENAME) VALUES('RAMESH')
INSERT INTO EMP1(ENAME) VALUES('RAHUL')

SELECT * FROM EMP1

DELETE FROM EMP1
WHERE ENO=1050

SELECT * FROM EMP1

INSERT INTO EMP1(ENAME) VALUES('RAHUL')

SELECT * FROM EMP1

DELETE FROM EMP1
Here we deleted all the records from emp1 table,but identity will not be reset .

SELECT * FROM EMP1

INSERT INTO EMP1(ENAME) VALUES('RAHUL')

TRUNCATE TABLE EMP1
if we use truncate identity will be reset.
SELECT * FROM EMP1

INSERT INTO EMP1(ENAME) VALUES('RAHUL')

This insert will start with seed
We can also use command to reset the identity instead of using truncate but best approach is we can reset using truncate.

Synatx:

DBCC CHECKIDENT('<TABLE_NAME>',RESEED,<INITIAL_VALUE>)

EXAMPLE:

DBCC CHECKIDENT('EMP1',RESEED,1000)

Database console check point by using this we can able to reset

INSERT INTO EMP1(ENAME) VALUES('SRINIVAS')
INSERT INTO EMP1(ENAME) VALUES('ASHOK')
INSERT INTO EMP1(ENAME) VALUES('SURESH')

INSERT INTO EMP1(ENAME) VALUES('RAMESH')

SELECT * FROM EMP1

Thanks
GSV