How do I query mysql data with array

I have 2 tables colorcode & users

colorcode

ID colorid  colorname
------------------------
1  1        yellow
2  2        black
3  3        red
4  4        white

users

ID userid  colorid
------------------------
1  1        1,2
2  2        3,4
3  3        1,3,4
4  4        1

How do I retrieve & query individual colorid 开发者_开发问答

$aa = $db->query("SELECT * FROM colorcode"); 
$colors = array();
   while ($colordata = mysql_fetch_assoc($aa)) {
   $colors[] = $colordata["colorid"];
}

Let's say I want query which users have yellow color & what it's the statement should I use for users

SELECT .. FROM users
WHERE colorid ....

It's a bad design... since you're trying to access the individual color_ids in the user table, but have stored them as a comma-separated list, you canot have the database do a normal join for you - you've killed off the main point of using a relational database by making it impossible to for the database to do the relating for you.

However, since you're on mysql, you're in luck - mysql has a function for cases like this:

SELECT users.ID, userid, GROUP_CONCAT(colorcode.colorname)
FROM users
LEFT JOIN colorcode ON FIND_IN_SET(colorcode.ID, users.colorid)
GROUP BY users.id

SELECT * FROM users
WHERE colorid LIKE "%1%"

But what I would really do is make a link table from users to colors:

usersToColors:

ID userid  colorid
------------------------
1  1        1
2  1        2
3  2        3
4  2        4
...

Then you could do:

SELECT * FROM users u, usersToColors utc
WHERE u.userid = utc.userid 
      AND utc.colorid = 1;

Or even:

SELECT * FROM users u, usersToColors utc, colors c
WHERE u.userid = utc.userid 
      AND utc.colorid = c.colorid
      AND c.colorname = "yellow";