Sets a search condition to return a specific subset of data.
IF search-condition
THEN expression1
[ ELSE expression2 ]
ENDIF
This expression returns the following:
If search-condition is TRUE, the IF expression returns expression1.
If search-condition is FALSE and an ELSE clause is specified, the IF expression returns expression2.
If search-condition is FALSE, and there is no expression2, the IF expression returns NULL.
If search-condition is UNKNOWN, the IF expression returns NULL.