Use this statement to control conditional execution of a SQL statement, as an alternative to the Watcom-SQL IF statement.
IF expression statement
[ ELSE [ IF expression ] statement ]
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.
SQL/2003 Transact-SQL extension.
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