sql - 加入 2 个表时遇到问题

Question

我已经尽我所能尝试了，但我很难找出这个查询的问题。

当我执行查询时，它会从 table 中带来重复的行deleted_messages。我正在private_messages与deleted_messages. deleted_messages保留已被用户完全删除的那些消息。

SELECT private_messages.EA_MID
    ,private_messages.EA_to
    ,private_messages.EA_from
    ,private_messages.EA_DateSent
    ,private_messages.EA_Subject
    ,private_messages.EA_Message
    ,private_messages.EA_Opened
    ,private_messages.EA_RecipientDeleted
    ,private_messages.EA_SenderDeleted
    ,deleted_messages.EA_DMID
    ,deleted_messages.EA_UID
    ,deleted_messages.EA_MID
    ,deleted_messages.EA_Date
FROM deleted_messages
LEFT JOIN private_messages ON (deleted_messages.EA_UID = private_messages.EA_to)
    OR (deleted_messages.EA_UID = private_messages.EA_from)
WHERE (
        (
            private_messages.EA_to = '$uid'
            AND private_messages.EA_RecipientDeleted = '1'
            )
        OR (
            private_messages.EA_from = '$uid'
            AND private_messages.EA_SenderDeleted = '1'
            )
        )

Answer 1

SELECT /* field omitted  */
FROM deleted_messages
LEFT JOIN private_messages 
    ON (deleted_messages.EA_UID = private_messages.EA_to 
         AND private_messages.EA_RecipientDeleted = '1')
    OR (deleted_messages.EA_UID = private_messages.EA_from 
         AND private_messages.EA_SenderDeleted = '1')
WHERE /* omitted */