Question

我在mysql表中有一个列，列出了游戏中的获胜者。我正在尝试找到一个查询，它将为每个玩家返回最长的胜利。或者用php解释查询的方法。

在这种情况下，它会凯特4， Ed 1，迈克2，哈利1，

**Winner**
Kate
Kate
Ed
Harry
Ed
Harry
Mike
Mike
Ed
Harry
Kate    
Kate  
Kate
Kate
Ed

提前道歉，因为我对这一切都很陌生。

Answer 1

SELECT winner, MAX(winningStreak) FROM (
SELECT
winner,
IF(winner=@prev, @rownum:=@rownum+1, @rownum:=1) AS winningStreak,
@prev:=winner
FROM
yourTable
, (SELECT @prev:=NULL, @rownum:=1) vars
/*ORDER BY whateverDeterminesTheOrderOfTheWinners*/
)sq
GROUP BY winner
ORDER BY winningStreak DESC

您需要另一列来确定获奖者的顺序，就像您列出的那样，并调整查询的已过时部分。除此之外，这个查询有效，但在PHP中实际上更容易完成。

直播here。

Answer 2

使用变量会使查询更简单，但我想用SQL来解决它。这是我的问题：

SELECT winner, COALESCE(MAX(id2-min_id1), 0)+1
FROM (
  SELECT MIN(w1.id) min_id1, w1.winner, w2.id id2
  FROM
    winners w1 LEFT JOIN winners w2
    ON w1.id < w2.id
       AND w1.winner = w2.winner
  WHERE
    NOT EXISTS (SELECT NULL FROM winners w3
                WHERE w3.winner != w1.winner
                      AND w3.id > w1.id AND w3.id < w2.id)
  GROUP BY
    w2.id, w1.winner
  ) s
GROUP BY
  winner

请参阅小提琴here。我正在使用ID，因为没有ID或时间戳，无法确定SQL查询返回的行的顺序。这假设ID没有间隙。

Answer 3

好的，轮到我...这假设id是auto_incrementing，没有间隙......

SELECT winner
     , MAX(streak) longest_streak
  FROM
     ( SELECT a.*
            , MIN( c.id ) - a.id + 1 streak
         FROM results a
         LEFT 
         JOIN results b 
           ON a.id = b.id + 1 
          AND b.winner = a.winner
         LEFT 
         JOIN results c 
           ON a.id <= c.id 
          AND c.winner = a.winner
         LEFT 
         JOIN results d 
           ON c.id = d.id - 1 
          AND d.winner = a.winner
        WHERE b.id IS NULL
          AND c.id IS NOT NULL
          AND d.id IS NULL
        GROUP 
           BY a.id
     ) x
 GROUP
    BY winner
 ORDER  
    BY longest_streak DESC;

mysql查询查找列中运行时间最长的查询

3 个答案: