一条sql执行出现错误Unknown column 'e.sal' in 'on clause'_endless_fighting的博客

先贴出我执行的sql，表面上看没啥错误啊

SELECT e.ename,e.sal,d.dname FROM employee e ,dept d
JOIN
(SELECT MAX(sal) AS sal FROM employee WHERE deptnu=30 ) s
ON
e.sal>s.sal
WHERE
e.deptnu=d.deptnu;SELECT e.ename,e.sal,d.d