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IDENTITY COLUMNS


Identity column specifies when ever new value is inserted into table. Identity column automatically inserted value into column.

Identity Column can be specified at the time of creation of table.

CREATE TABLE Employee
(
 EMPID INT IDENTITY(1,1),
 EMPNAME VARCHAR(50),
 SALARY INT
)

In above table creation script EMPID column specifies IDENTITY property i.e., whenever a new row inserted into a Employee table EMPID Column will automatically value is inserted.

INSERT INTO Employee (EMPNAME,SALARY)VALUES('RAKESH',7000)

INSERT INTO Employee (EMPNAME,SALARY)VALUES('ALI',12000)

SELECT * FROM Employee
When u run above select statement is the following result is





























if u are trying insert value into identify columns .it will give error.

INSERT INTO Employee (EMPID,EMPNAME,SALARY)VALUES(1,'RAKESH',7000)

Msg 544, Level 16, State 1, Line 1
Cannot insert explicit value for identity column in table 'Employee' when IDENTITY_INSERT is set to OFF.

 Please refer this link HOW TO INSERT VALUE INTO IDENTITY COLUMN



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