MySQL MySQL查询AND OR运算符逻辑
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MySQL query AND OR operator Logic
提问by ronnockoch
I'm in the middle of a project for my Comp Science project for monday, and i came across a MySQL question regarding a Query.
我正在为我的 Comp Science 项目做一个周一的项目，我遇到了一个关于查询的 MySQL 问题。
What I want to achieve, through words is this.
我想通过文字实现的就是这个。
If the column to=jake and column from=connorOR column to=connor and column from=jakeget the cID from that specific table.
如果列to=jake 和列 from=connorOR列 to=connor 和列 from=jake从该特定表中获取 cID。
What I have so far is this
到目前为止我所拥有的是这个
$query="SELECT cID FROM conversation WHERE to='$to' AND to='$from' OR to='$from' AND from='$to'";
What is there that I can do to get this query to work? Thanks in advance!
我可以做些什么来使此查询正常工作？提前致谢！
回答by Michael Berkowski
You just need a couple pairs of ()to group the two conditional pairs, separated by a logical OR
您只需要几对()来将两个条件对分组，并由逻辑分隔OR
$query="
SELECT cID
FROM conversation
WHERE
/* to Jake, from Connor */
(`to`='$to' AND `from`='$from')
/* OR to connor, from jake */
OR (`to`='$from' AND `from`='$to')";
Note: FROMand TOare both MySQL reserved keyword, and thus require quoting with backticks.
注意：FROMandTO都是MySQL 保留关键字，因此需要用反引号引用。
回答by Stefan
This is untested but I would think you need to put the to='$to' AND to='$from' (which should be from not to i guess??) into brackets??
这是未经测试的，但我认为您需要将 to='$to' AND to='$from' （应该是 from not to 我猜？？）放入括号中？？
Just realised someone else put this as i was typing it
刚刚意识到有人在我打字的时候把这个放了
回答by Tschallacka
$query="SELECT cID FROM conversation WHERE
(to='$to' OR to='$from' OR to='$from') AND from='$to'";
