If Condition in SQL

If...Else statement is used to test a condition. If we have more than 1 condition we can use If...Else statement. We can also have nested If...Else statements also. We have nested If...Else statements when we have to include 1 or more If...Else statements in 1 If...Else statement. If...Else Statement in SQL is used in execution os Stored Procedures.

Syntax for simple If...Else statement is,

IF ( Condition )
BEGIN
Sql Statements
END
ELSE
BEGIN
Sql Statements
END

Syntax for nested If...Else statements is,

IF ( Condition )
BEGIN
Sql Statements
IF ( Condition )
BEGIN
Sql Statements
END
ELSE
BEGIN
Sql Statements
END
END

ELSE
BEGIN
Sql Statements
END


Example for simple If...Else statement is,

CREATE PROCEDURE [dbo].[USP_InsertUserSession]
@userId int,
@userSession nvarchar(255),
@userDate datetime,

AS
BEGIN
declare @tmpuserId int
SELECT @tmpuserId=userId from UsersSessions WHERE userId=@userId

if @tmpuserId > 0
begin
UPDATE UsersSessions SET userSession=@userSession, userDate=@userDate WHERE userId=@tmpuserId
end

else
begin
INSERT INTO UsersSessions(userId,userSession,userDate) VALUES (@userId,@userSession,@userDate)
end