ALL tests that a value is true when compared to every value in a list returned by a subquery. The complete syntax for
<value> <comparison_operator> ALL (<subquery>)
For example, the following cursor retrieves information about employees whose salaries are larger than that of the vice president of channel marketing:
EXEC SQL DECLARE MORE_THAN_VP CURSOR FOR SELECT LAST_NAME, FIRST_NAME, SALARY FROM EMPLOYEE WHERE SALARY > ALL (SELECT SALARY FROM EMPLOYEE WHERE DEPT_NO = 7734);
ALL returns Unknown if the subquery returns a
NULL value. It can also return Unknown if the value to be compared is
NULL and the subquery returns any non-
NULL data. If the value is
NULL and the subquery returns an empty set, ALL evaluates to True.
For more information about subqueries, see Using Subqueries.