Question

我有问题,说明如何在我 below的提问中作案陈述。基本上,问询只是从电文中提取电流,即把发送的当前用户(喷洒)或发送的原始透镜(翻新)发送。这为每个人提供了完美的选任书,但原版的投稿人除外,他们应当能够拿到与透镜有关的所有信息。

Basically I need to add the SQL equivalent of the following statement:

WHERE messages_threads.id = $threadid
     if($userid == messages_threads.senderid) {
        // Don t add an AND clause
     } else {
        // Add the following AND clause
        AND (messages_messages.senderid = $userid OR messages_messages.senderid = messages_threads.senderid)
     }

Here s the query I m currently using:

SELECT messages_messages.id, messages_messages.senderid, username AS sendername, pictures.url AS picture, body, UNIX_TIMESTAMP(time) AS unixtimestamp
        FROM messages_messages
        JOIN messages_threads ON messages_threads.id = messages_messages.threadid
        JOIN users ON messages_messages.senderid = users.id
        LEFT JOIN pictures ON messages_messages.senderid = pictures.userid AND pictures.profile = 1
        WHERE messages_threads.id = $threadid
        AND (messages_messages.senderid = $userid OR messages_messages.senderid = messages_threads.senderid)
        ORDER BY time ASC

Answer 1

声明可转换成附和或:

WHERE messages_threads.id = $threadid AND 
    ($userid=messages_threads.senderid OR                       
        (messages_messages.senderid = $userid OR 
         messages_messages.senderid = messages_threads.senderid))

如果$userid=messages_threads.senderid 即整个<代码>或条款是真实的,因此没有任何东西可以检查。如果是假的,则对条款的其余部分进行检查。

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