How to insert values into IDENTITY column

Identity columns commonly used as primary keys in tables. These columns are automatically values are assigned when ever new record inserted into a table.

IF OBJECT_ID('Employee','U') IS NOT NULL

DROP TABLE Employee

Ceating the Emlployee table

CREATE TABLE Employee

(

ID INT IDENTITY(1,1) PRIMARY KEY ,

NAME VARCHAR(20),

SALARY INT

)

INSERT INTO Employee

SELECT 'Rakesh',5000

UNION ALL

SELECT 'Ramu',6000

UNION ALL

SELECT 'Naresh',7000

SELECT * FROM Employee

In below scenario trying to insert value into identity column.

INSERT INTO Employee (ID,NAME,SALARY) VALUES(4,'Sravan',10000)

When ever tring to insert value into idenity column of ID we get follwing follwing error.

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.

By enabling IDENTITY_INSERT on a table insert value into identity column.

SET IDENTITY_INSERT Employee ON

INSERT INTO Employee (ID,NAME,SALARY) VALUES(4,'Sravan',10000)

SET IDENTITY_INSERT Employee OFF

(1 row(s) affected)

SELECT * FROM Employee

Key points about IDENTITY_INSERT:

· It can only be enabled on one table at a time.

· When it is enabled on a table you must specify a value for the identity column.

· The user issuing the statement must own the object, be a system administrator (sysadmin role), be the database owner (duo) or be a member of the db_ddladmin role in order to run the command

Comments

SET ROWCOUNT

Stop the processing after the number of rows has been affected. Example: Step-1: Create the Table and insert some sample data. CREATE TABLE STUDENT ( ID INT IDENTITY ( 1 , 1 ) PRIMARY KEY , STUDENTNAME VARCHAR ( 100 ) NOT NULL , LIVINGLOCATION VARCHAR ( 100 ) NULL ) INSERT INTO STUDENT ( STUDENTNAME , LIVINGLOCATION ) SELECT 'Rakesh' , 'Hyderabad' UNION ALL SELECT 'Raju' , 'Delhi' UNION ALL SELECT 'Madhu' , 'Hyderabad' UNION ALL SELECT 'Naresh' ,NULL UNION ALL SELECT 'Venaktesh' , 'Chennai' In above Insert Statement we inserted 5 sample records. Step-2: Using SET ROWCOUT SET ROWCOUNT 3 ; SELECT * FROM STUDENT ORDER BY ID DESC It will affected 3 rows after that processing has been stopped. Step-2: Using SET ROWCOUT 0 SET ROWCOUNT 0 ; SELECT * FROM STUDENT ORDER BY ID DESC ...

Simple Trick Using ISNULL

Simple Trick Using ISNULL: Step-1: Create Sample Student Table. CREATE TABLE Student ( Id INT IDENTITY ( 1 , 1 ) PRIMARY KEY , StudentName VARCHAR ( 100 ) NOT NULL, LivingLocation VARCHAR ( 100 ) NULL ) Step-2 :Insert Some Sample Data INSERT INTO Student SELECT 'Rakesh' , 'Hyderabad' UNION ALL SELECT 'Raju' , 'Delhi' UNION ALL SELECT 'Madhu' , 'Hyderabad' UNION ALL SELECT 'Naresh' ,NULL UNION ALL SELECT 'Venaktesh' , 'Chennai' Step-3 : Select Data from Student Table SELECT * FROM Student If we observe above data of student table we have student id 4 record LivingLocation is NULL. Step -4 :Select Data from Student Table With Where Clause. SELECT * FROM Student WHERE LivingLocation = 'Hyderabad' In the above query we are included the where clause w...

Coalesce function

Coalesce function returns the first non-null value among the arguments. Syntax: Coalesce (expression [,..n]) Here is example using Coalesce function Example 1 DECLARE @Str1 varchar ( 10 ), @str2 varchar ( 20 ), @Str3 varchar ( 20 ) SET @Str2 = 'Sql' , @Str3 = 'Server' SELECT COALESCE ( @Str1 , @str2 , @Str3 ) As [Coalesce] In above example @Str2 value is ‘Sql’ , @str3 value is ‘Server’ and @str1 values is Null because it not assigned any value . Output: It return’s “Sql” because Coalesce function return’s first non null value. Example 2: Coalesce in select statement. IF OBJECT_ID ( 'Employee' , 'U' ) IS NOT NULL DROP TABLE Employee CREATE TABLE Employee ( ID INT IDENTITY ( 1 , 1 ) PRIMARY KEY , NAME VARCHAR ( 20 ), SALARY INT ) INSERT INTO Employee ( NAME , SALARY ) VALUES ( 'Rakesh' , 5000 ),(NULL, 6000 ),( 'Naresh...

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