ASA SQL Reference
  SQL Statements

IF statement [T-SQL]

Description 

Use this statement to control conditional execution of a SQL statement, as an alternative to the Watcom-SQL IF statement.

Syntax 

 IF expression
statement
[ ELSE
[ IF expression ]
statement ]

Usage 

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.

Permissions 

None.

Side effects 

None.

Standards and compatibility 

• SQL/92    Transact-SQL extension.

• SQL/99    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

      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