Question

我每次发生时都会报告用户的分数。现在我想显示用户的最高分。表格设置如下：

玩家（身份证，姓名）

PlayerHasAchievement（id，playerId，   achievementId）

成就（身份，类型，金额，时间）

这就是我现在所拥有的：

    $query = "SELECT MAX(ach.amount) as amount, p.username, ach.time
                FROM  achievement as ach
                INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.id
                INNER JOIN player as p ON p.userId = playAch.userid
                WHERE ach.type = 2
                GROUP BY amount
                ORDER by `amount` DESC
                LIMIT $amount";

我试图明确地选择它但它不起作用。我很难过，它应该很容易！感谢您的阅读，我将不胜感激任何帮助！

Answer 1

问题是您获得的ach.time与MAX(amount)的行不同。加入另一个子查询以首先获得MAX(amount)。

注意：在您发布的表格定义中，playerHasAchievement有一个字段playerId而不是userId

SELECT MAX(ach.amount) as amount, p.username, MAX(ach.time) MaxTime
FROM  achievement as ach
  INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.id
  INNER JOIN player as p ON p.userId = playAch.playerId
  INNER JOIN (
    SELECT playAch.playerId, MAX(ach.amount) as MaxAmount
    FROM  achievement as ach
      INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.id
    WHERE ach.type = 2
    GROUP BY playAch.playerId
  ) g ON p.playerId = g.playerId AND ach.amount = g.MaxAmount
WHERE ach.type = 2
GROUP BY p.playerId
ORDER by `amount` DESC
LIMIT $amount";

我们将外部查询分组的原因是为了避免关系 - 比如一个玩家两次得分相同。

Answer 2

在第3行的加入中，你真的不想要

INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.achievementId

和其他人都是正确的，您需要按非聚合列进行分组，而不是聚合列。

假设您的数据库布局与问题中指定的一样，那就是我将使用的查询。

SELECT ach.amount, p.Name, ach.time
  FROM achievement as ach
   JOIN playerHasAchievement as playAch ON ach.id=playAch.achievementId
   JOIN player AS p ON p.id = playAch.playerId
 WHERE ach.type = 2
   AND ach.amount = (SELECT MAX(ach.amount)
                     FROM achievement as ach
                     JOIN playerHasAchievement as playAch ON ach.id=playAch.achievementId
                     JOIN player AS p ON p.id = playAch.playerId
                     WHERE ach.type = 2)
 GROUP BY ach.amount
 ORDER by ach.time

取第一个结果（如果有相同分数的倍数）将给你高分和最低时间。

希望有所帮助！

Answer 3

您没有正确使用群组，因为您只是按金额分组。用户名和时间怎么样？

SQL查询问题

3 个答案: