Reference Manual
   CHAPTER 9. SQL Statements     

IF statement [T-SQL]

Function 

To provide conditional execution of a SQL statement, as an alternative to the Watcom-SQL IF statement.

Syntax 

IF expression
... statement
... [ ELSE
... [ IF expression ]
... statement ]

Authorization 

None.

Side effects 

None.

Description 

The Transact-SQL IF conditional and the ELSE conditional each control the performance 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.

Standards and compatibility 

• SQL/92     Transact-SQL extension.

• Sybase     Adaptive Server Enterprise supports the Transact-SQL IF statement.

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