防止MySQL中左连接与内部连接的重复

这是我的sql。如果matches\u times表中存在重复条目，则无法过滤查询中的重复项

SELECT
  info.user_id,
  info.name,
  info.age,
  info.gender,
  DATE_FORMAT(likes.time, '%c/%e/%y') AS matchedTime,
  DATE_FORMAT(matches_times.proposed_time, '%b %d, %Y @ %h:%i %p') AS proposedTime,
    matches_times.agreed
FROM info
INNER JOIN likes
  ON info.user_id = likes.liked_user_id
  AND likes.user_id = ?
LEFT JOIN matches_times
  ON (info.user_id = matches_times.user_id_1 OR info.user_id = matches_times.user_id_2)
  AND (matches_times.user_id_1 = ? OR matches_times.user_id_2 = ?)
WHERE likes.liked_user_id IN (SELECT
  user_id
FROM likes
WHERE likes.liked_user_id = ?)
ORDER BY
    CASE 
      WHEN matches_times.proposed_time IS NULL THEN likes.time 
      WHEN matches_times.proposed_time IS NOT NULL THEN matches_times.proposed_time
    END DESC

三个表格如下：

喜欢 信息 比赛时间 编辑：

这里描述了这个问题

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一个简单的方法是基于这样一个事实，即您可以使用具有distinct（o等效视图）的子选择

在选择中，参考t.U时间

如果您需要max，则不需要distinct，但需要group by，例如：

LEFT JOIN (

    select  user_id_1, user_id_2,  max(DATE_FORMAT(proposed_time, '%b %d, %Y @ %h:%i %p')) as proposed_time
    from matches_times
    group by user_id_1, user_id_2

) t  ON (info.user_id = t.user_id_1 OR info.user_id = t.user_id_2)
  AND (t.user_id_1 = ? OR t.user_id_2 = ?)

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mysql或sql server？请参阅提供一些示例数据以及该示例数据的预期结果。感谢您的帮助。虽然“字段列表”中的“未知列”匹配了\u次。建议的\u次，现在没有错误，但仍然得到与我的pic相同的结果，但是我得到了这个错误。我是错过了什么，还是我只是个傻瓜？你有两个不同的时间，所以你得到了两排。。你可能需要这个的最大值或最小值。。然后你只得到一行你能举个例子吗？我不确定我是否100%@lazyboy78答案更新。。希望我的回答有用（至少）

id(pk) | user_id | name | age | gender | timestamp

id(pk) | user_id_1 | user_id_2 | proposed_time | agreed | timestamp

LEFT JOIN (

    select distinct user_id_1, user_id_2,  DATE_FORMAT(proposed_time, '%b %d, %Y @ %h:%i %p') as proposed_time
    from matches_times

) t  ON (info.user_id = t.user_id_1 OR info.user_id = t.user_id_2)
  AND (t.user_id_1 = ? OR t.user_id_2 = ?)

LEFT JOIN (

    select  user_id_1, user_id_2,  max(DATE_FORMAT(proposed_time, '%b %d, %Y @ %h:%i %p')) as proposed_time
    from matches_times
    group by user_id_1, user_id_2

) t  ON (info.user_id = t.user_id_1 OR info.user_id = t.user_id_2)
  AND (t.user_id_1 = ? OR t.user_id_2 = ?)