mysql查询记录添加序列号，数据相同的序列号一样

    select t.dept_no,t.rank from employee e,
    (
    SELECT
    (@rowNO := @rowNo+1) rank,
    dept_no
FROM
    (SELECT dept_no FROM employee group BY dept_no ) dept_no,
    (SELECT @rowNO :=0) row
    ) t where e.dept_no = t.dept_no