有一个积分表，积分从高往下排，怎么取出其中的一个用户的排名，积分

select a.username,(@rowNum:[email protected]+1) as c,a.integral as 积分
from xs_user a,(Select (@rowNum :=0 ) ) b order by integral DESC,time

SELECT * FORM 
  (
    select a.username,(@rowNum:[email protected]+1) as c,a.integral as 积分
    from xs_user a,(Select (@rowNum :=0 ) ) b order by integral DESC,time
  ) T
 WHERE username='XXX'