Question: I want to execute a query where I can find one ID in a list of ID.

table `user` 

```
id_user | name  | id_site
-------------------------
1       | james | 1, 2, 3 
1       | brad  | 1, 3 
1       | suko  | 4, 5

```

and my query (doesn't work)

```
SELECT * FROM `user` WHERE 3 IN (`id_site`) 

```

This query work (but doesn't do the job) 

```
SELECT * FROM `user` WHERE 3 IN (1, 2, 3, 4, 6) 

```

Answer: 
Try this: [FIND\_IN\_SET(str,strlist)](http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_find-in-set)
The WHERE IN clause is useful to replace many OR conditions.
For exemple

```
SELECT * FROM `user` WHERE id IN (1,2,3,4)

```

is cleaner than

```
SELECT * FROM `user` WHERE id=1 OR id=2 OR id=3 OR id=4

```

You're just trying to use it in a wrong way.

Correct way :

```
WHERE `field` IN (list_item1, list_item2 [, list_itemX])

```