1.--dense_rank()分析函数(查找每个部门工资最高前三名员工信息) select * from (select deptno,ename,sal,dense_rank() over(partition by deptno order by sal desc) a from scott.emp) where a<=3 order by deptno asc,sal desc ; 结果: --rank()分析函数(运行结果与上语句相同) select * from (select dep