mysql select 语句查询排名

SELECT

    obj.MEM_ID,

    obj.count,

    CASE

WHEN @rowtotal = obj.count THEN

    @rownum

WHEN @rowtotal := obj.count THEN

    @rownum :=@rownum + 1

WHEN @rowtotal = 0 THEN

    @rownum :=@rownum + 1

END AS rownum

FROM

    (
SELECT
c.MEM_ID,
count(*) count
FROM
T_CIRCLE_INTEREST c
WHERE
c.DELETED = 'N'
AND c.MEM_ID_ED IN (
SELECT
MEM_ID
FROM
T_TEACHER t
WHERE
t.DELETED = 'N'
)
GROUP BY
c.MEM_ID 

) AS obj,

    (SELECT @rownum := 0 ,@rowtotal := NULL) r

ORDER BY obj.count desc