前言：Oracle中row_number() over分析函數，有時使用來解決問題非常方便，但最近項目用mysql處理數據需用到類似功能，找了下在mysql中沒有類似的函數，此處記錄使用mysql變量來模擬類似效果。
SQL語句如下：
SELECT * FROM
(SELECT
F.PARTY_ID AS PARTY_ID,
F.ALL_COUNT AS ALL_COUNT,
F.SU AS SU,
CASE
WHEN @PARTY_ID != PARTY_ID THEN
@ROWNUM := 1
ELSE
@ROWNUM :=@ROWNUM + 1
END AS ROWNUM,
@PARTY_ID := PARTY_ID AS PARTY_ID12
FROM
(SELECT @F.PARTY_ID := “”) c,
(SELECT @ROWNUM := 0) r,
(
SELECT
E.PARTY_ID AS PARTY_ID,
E.SU AS SU,
E.ALL_COUNT AS ALL_COUNT
FROM
(
SELECT
c.PARTY_ID AS PARTY_ID,
COUNT(*) AS SU,
d.AMT AS ALL_COUNT
FROM
dpf_ckaccno_dtl d
JOIN dpf_ckaccno c ON d.ACC_NO = c.DM01ACCT
WHERE
d.CRDFLG = ‘D’
GROUP BY
c.PARTY_ID,
d.AMT
) E
ORDER BY
E.PARTY_ID,
E.SU DESC,
E.ALL_COUNT DESC
) F ) G WHERE G.ROWNUM<=3
說明：1、（SELECT @ROWNUM := 0）r 用於定義變量並初始化，後面是命別名，此處不能省略，不然會報錯。
2、 @PARTY_ID := PARTY_ID AS PARTY_ID12 此處是把當前行值賦值給PARTY_ID 變量，前面(SELECT @F.PARTY_ID := “”) c，已經將其初始化爲空串
3、CASE
WHEN @PARTY_ID != PARTY_ID THEN
@ROWNUM := 1
ELSE
@ROWNUM :=@ROWNUM + 1
END AS ROWNUM, – 此處通過case when 條件句來判斷變量值與當前PARTY_ID是否相等來，不等說明是新的PARTY_ID，ROWNUM 就爲1，否則就+1
4、通過這個sql，我們可以發現mysql在sql語句中使用變量時，初始化的東西放到from語句的後面，使變量的變化語句要放到查詢結果裏面，這裏的原因可能是跟數據庫管理系統解析一個sql的順序有關係吧（猜的！！！）
結果如下：
參考：mysql中實現row_number() over(http://www.zhimengzhe.com/shujuku/MySQL/117054.html)