为什莫数据重复了?以及我要怎么解决这个问题?
SELECT e.ename , e.sal , s.grade
FROM emp e,salgrade s
WHERE e.sal
BETWEEN s.losal AND s.hisal AND
SELECT e.ename , e.sal , s.grade
FROM emp e,salgrade s
WHERE e.sal
BETWEEN s.losal AND s.hisal AND