Skip to main content

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



Labels:

Comments

Post a Comment

Popular posts from this blog

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 ...
7 comments
Read more

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...
1 comment
Read more

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...
3 comments
Read more