親測無誤

小提示：
建立臨時表的方式需要資料庫寫許可權，只有讀許可權的話還是用老實用巢狀sql好了

DROP TEMPORARY TABLE IF EXISTS tableWithRowNum;
CREATE TEMPORARY TABLE tableWithRowNum
  SELECT @rownum := @rownum + 1 AS rowNum, b.*
  FROM (
    SELECT @rownum := 0 AS rowNum
  ) a, (
    SELECT *
    FROM `<targetTable>`
    ORDER BY
 
 `<groupByCol>`, `<orderByCol>` DESC
  ) b;
DROP TEMPORARY TABLE IF EXISTS eachGroupMinRowNum;
CREATE TEMPORARY TABLE eachGroupMinRowNum
  SELECT `<groupByCol>`, MIN(rowNum) AS minRowNum
  FROM tableWithRowNum
  GROUP BY `<groupByCol>`;
SELECT t.*
FROM eachGroupMinRowNum l, tableWithRowNum t
WHERE
 
 l.`<groupByCol>` = t.`<groupByCol>`
  AND t.rowNum - l.minRowNum < '<linesPerGroup>';

個人例項

定義儲存過程：

delimiter $$

drop PROCEDURE if exists select_daily_top_gold$$

CREATE PROCEDURE select_daily_top_gold(IN topN INT)
BEGIN

DROP TEMPORARY TABLE IF EXISTS dailyUserSumGold;

CREATE
 
 TEMPORARY TABLE dailyUserSumGold
AS
SELECT `user_id`, SUM(`gold`) AS sum_gold
 , LEFT(`create_time`, 10) AS daystr
FROM `ml_user_gold`
GROUP BY daystr, `user_id`;

DROP TEMPORARY TABLE IF EXISTS tableWithRowNum;

CREATE TEMPORARY TABLE tableWithRowNum
AS
SELECT @rownum := @rownum + 1 AS rowNum, b.*
FROM (
 SELECT @rownum := 0 AS rowNum
) a, (
  SELECT *
  FROM dailyUserSumGold
  ORDER BY daystr, sum_gold DESC
 ) b;

DROP TEMPORARY TABLE IF EXISTS eachGroupMinRowNum;

CREATE TEMPORARY TABLE eachGroupMinRowNum
AS
SELECT daystr, MIN(rowNum) AS minRowNum
FROM tableWithRowNum
GROUP BY daystr;

END $$

delimiter ;

呼叫儲存過程：

call select_daily_top_gold(2);
SELECT t.*
FROM eachGroupMinRowNum l, tableWithRowNum t
WHERE l.`daystr` = t.`daystr`
 AND t.rowNum - l.minRowNum < 5;