mysq的rownumber()Over()

SELECT
@rownum :=@rownum + 1 AS rownum,
t.id,
t.marketValue,
t.createtime,

IF (
@pcode = t.`code`,@rank :=@rank + 1 ,@rank := 1
) AS rank,
@pcode := `code` AS `code`
FROM
(
SELECT
t1.id,
t1.`code`,
t1.marketValue,
t1.createtime
FROM
c_stock_data_info t1
) t,
(
SELECT
@rownum := 0,@pcode:=null,@rank := 0
) a
ORDER BY
t.`code`,
t.createtime DESC