Weird MySQL SELECT WHERE IN problem

Question

I'm trying to do this:

SELECT * FROM library WHERE $cat IN (tags);

Say that I have $cat = '15'; and tags is a fieldname in library that looks like this: 2,15,34, 45 How can I get it to work? I understand that normally the $var should be after the IN ($var), but the imploded array sits in my DB and not in the $var - somehow I've gotten it the wrong way around and I just cannot figure it out - Please help me, I'm wasting days :)

Answer 1

You can use FIND_IN_SET instead, like this:

SELECT * FROM library
WHERE FIND_IN_SET($cat, tags);

Answer 2

从库中选择*，其中'％，$ cat，％'等标签;

Answer 3

你不会这样做：

SELECT * FROM library WHERE tags = $cat