An EXISTS predicate tests for the existence of matching rows.
EXISTS
NOT
( fullselect )
SELECT ID, JOB ANSWER
FROM STAFF A =========
WHERE EXISTS ID JOB
(SELECT * --- -----
FROM STAFF B 10 Mgr
WHERE B.ID = A.ID 20 Sales
AND B.ID < 50) 30 Mgr
ORDER BY ID; 40 Sales
An EXISTS predicate tests for the existence of matching rows.
EXISTS
NOT
( fullselect )
SELECT ID, JOB ANSWER
FROM STAFF A =========
WHERE EXISTS ID JOB
(SELECT * --- -----
FROM STAFF B 10 Mgr
WHERE B.ID = A.ID 20 Sales
AND B.ID < 50) 30 Mgr
ORDER BY ID; 40 Sales