[오늘쿼리] EXISTS NOT EXISTS

SELECT * 
	FROM DEPT D
    WHERE EXISTS (SELECT *
    				FROM EMP E
                    WHERE E.DEPTNO = D.DEPTNO)

결과

DEPTNO | DNAME | LOC
10 | ACCOUNTING | NEW YORK
30 | SALES | CHICAGO
20 | RESEARCH | DALLAS

SELECT * 
	FROM DEPT D
    WHERE NOT EXISTS (SELECT *
    				FROM EMP E
                    WHERE E.DEPTNO = D.DEPTNO)

결과

DEPTNO | DNAME | LOC
40 | OPERATIONS | BOSTON