用于查找多个 ID 的最新时间戳的 SQL 查询

Question

我正在尝试运行一个查询，该查询返回特定用户组执行的最后一个“游戏”或操作。我不得不加入几张桌子才能最终得到我想要的东西，但这基本上现在返回了每个用户的游戏。我想参加他们的最后一场比赛。我在查询中将 max(___) 添加到时间戳，但它最终只返回了最近玩过的游戏，仅此而已。理想情况下，我希望看到每个用户及其最后的操作。

SELECT teamName, test_teams.userID, test_teams.timestamp AS signup, sponsorship, test_results.timestamp, stadium, win+draw+lose AS games 
    FROM test_teams 
INNER JOIN test_profile
    ON test_teams.userID = test_profile.userID
INNER JOIN test_results
    ON test_teams.userID = test_results.homeTeamId
WHERE test_teams.timestamp >= '2015-11-04 00:00:00' and win+draw+lose > 100
ORDER BY games desc;

Answer 1

以下 SQL 语句为您提供每个团队的最新时间戳/操作：

SELECT MAX(timestamp) as latestTimestamp, homeTeamId
  FROM test_results
  GROUP BY homeTeamId

它可以与其他2张表连接

SELECT teamName, tt.userID, tt.timestamp AS signup, sponsorship, tr.latestTimestamp, stadium, win+draw+lose AS games 
FROM test_teams tt
INNER JOIN test_profile
  ON test_teams.userID = test_profile.userID
INNER JOIN (
  SELECT MAX(timestamp) as latestTimestamp, homeTeamId
  FROM test_results
  GROUP BY homeTeamId) tr 
  ON test_teams.userID = tr.homeTeamId