MySQL查询使用AND＆amp; OR运营商

Question

下面的查询会加载所有会话，但是，我只想加载两个人之间的会话。

SELECT * FROM msg 
WHERE senderid = '{$sender}' 
OR recid = '{$recipient}' 
OR recid = '{$sender}' 
OR senderid = '{$recipient}' 
order by id asc

我如何使用AND＆amp; amp; OR运营商在一起？以下是否有效？

SELECT * FROM msg 
WHERE senderid = '{$sender}' 
AND recid = '{$recipient}' 
OR recid = '{$sender}' 
AND senderid = '{$recipient}' 
order by id asc

Answer 1

同时使用AND和OR时，请使用括号对逻辑进行分组，并确保它符合您的预期：

SELECT * FROM msg 
WHERE (senderid = '{$sender}' AND recid = '{$recipient}')
OR    (recid = '{$sender}' AND senderid = '{$recipient}')
order by id asc

Answer 2

请在下面找到。

SELECT * FROM msg 
WHERE (senderid = '{$sender}' AND recid = '{$recipient}') 
OR (recid = '{$sender}' AND senderid = '{$recipient}') 
order by id asc