SQL回炉之一：单表操作、函数小结

SQL回炉之一：单表操作、函数总结

--GROUP BY分组必须返回唯一值，有些东西必须用子查询SELECT * FROM emp ,(SELECT max(sal) max_sal FROM emp GROUP BY deptno)maxWHERE sal = max_sal;

SELECT FROM->WHERE->GROUP BY->HAVING->ORDER BY