등가조인과 비등가조인

SELECT
E.ENAME
,D.DNAME
,S.GRADE
FROM EMP E
INNER JOIN DEPT D -- 등가조인
ON E.DEPTNO = D.DEPTNO
JOIN SALGRADE S -- 비등가조인
ON E.SAL BETWEEN S.LOSAL AND S.HISAL
;