摘要：
用途--查询上下级 查询职位为总裁的雇员及其下属的相关信息 select empno, ename, job, mgr, deptno, level from emp start with job = 'PRESIDENT' connect by prior empno = mgr; 格式化 sel 阅读全文
摘要：
select group_id() gid, e.deptno, count(*) from emp e, salgrade s where sal between losal and hisal group by cube(e.deptno, e.deptno) order by deptno, 阅读全文