对所有员工的薪水按照salary进行按照1-N的排名

CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));

select t1.emp_no,t1.salary,count(distinct t2.salary) rank from (select * from salaries s where to_date = '9999-01-01') t1 , (select * from salaries s where to_date = '9999-01-01') t2 where t2.salary >= t1.salary group by t1.emp_no order by rank

(select * from salaries s where to_date = '9999-01-01') t1
(select * from salaries s where to_date = '9999-01-01') t2

select t1.emp_no,count(distinct t2.salary) from t1,t2 where t2.salary >= t1.salary group by t1.emp_no