这个不需要左联。SELECT r.title,
rt.text,
u.username
FROM reply as r,
topic as t,
reply_text as rt,
user as u
WHERE t.ID = '$_GET[TopicID]'
and r.TopicID = t.ID
and rt.ReplyID = r.ID and r.UID = u.ID;
rt.text,
u.username
FROM reply as r,
topic as t,
reply_text as rt,
user as u
WHERE t.ID = '$_GET[TopicID]'
and r.TopicID = t.ID
and rt.ReplyID = r.ID and r.UID = u.ID;
...
WHERE t.ID = '$_GET[TopicID]'
and r.TopicID = t.ID
and rt.ReplyID = r.ID and (r.UID = u.ID or r.UID=0);
打开表,选择关系图就可以了,要什么连接有什么连接,全部自动生成
就算有,那是别人的,自己写出来才是自己的
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只能说明前边的条件: t.ID = '$_GET[TopicID]'
and r.TopicID = t.ID
and rt.ReplyID = r.ID
出来的只有r.UID=0的记录。你可以将(r.UID = u.ID or r.UID=0) 这个条件去掉试试看。
FROM reply as r
INNER JOIN reply_text as rt ON r.ID=rt.ReplyID
LEFT JOIN user as u ON r.UID=u.ID OR r.UID=0
WHERE r.TopicID = '$_GET[TopicID]'
-----------
你的reply里没有ID字段啊
FROM reply as r
INNER JOIN reply_text as rt ON r.ID=rt.ReplyID
LEFT JOIN user as u ON r.UID=u.ID
WHERE r.TopicID = '$_GET[TopicID]'
就可以了