IF statement [T-SQL]

Controls conditional execution of a SQL statement, as an alternative to the Watcom SQL IF statement.

Syntax

 IF expression statement
[ ELSE [ IF expression ] statement ]

Remarks

The Transact-SQL IF conditional and the ELSE conditional each control the execution of only a single SQL statement or compound statement (between the keywords BEGIN and END).

In comparison to the Watcom SQL IF statement, there is no THEN in the Transact-SQL IF statement. The Transact-SQL version also has no ELSEIF or END IF keywords.

Privileges

None.

Side effects

None.

Standards

ANSI/ISO SQL Standard
Not in the standard.

Example

The following example illustrates the use of the Transact-SQL IF statement:

IF (SELECT max(ID) FROM sysobjects) < 100
   RETURN
ELSE
   BEGIN
      PRINT 'These are the user-created objects'
      SELECT name, type, ID
      FROM sysobjects
      WHERE ID < 100
   END

The following two statement blocks illustrate Transact-SQL and Watcom SQL compatibility:

/* Transact-SQL IF statement */
IF @v1 = 0
   PRINT '0'
ELSE IF @v1 = 1
   PRINT '1'
ELSE
   PRINT 'other'
/* Watcom SQL IF statement */
IF v1 = 0 THEN
   PRINT '0'
ELSEIF v1 = 1 THEN
   PRINT '1'
ELSE
   PRINT 'other'
END IF