PHP重复返回相同的结果

Question

When running a while script on my local xampp it just returns the same result over and over again, here's the PHP I'm using:

<?php
$id = $_GET['id'];
$getmembers = mysql_query("SELECT * FROM group_memberships WHERE groupid = $id LIMIT 10");
$getids = mysql_fetch_assoc($getmembers);
    while($id = $getids['userid']){
        $getusers = mysql_fetch_assoc(mysql_query("SELECT look, username FROM users WHERE id = '$id'"));
        echo ($getusers['username']);
        echo('<br />');
    }
?>

All that I get when I execute that is: http://prntscr.com/12nh6g My database contains 4 different users registered to that group. I'm not sure about joining tables in MySQL as I have no idea how to do it.

If I add a break; then it only returns one result, instead of timing out.

Any help is much appreciated!

Also I'm sorry about how messy the PHP is, I am new to this.

Answer 1

while($id = $getids['userid']){ #This condition will always be true.

Use your mysql_fetch_assoc statement in a loop like below.

while ($getids = mysql_fetch_assoc($getmembers)) {
    $id = $getids['userid']
    $getusers = mysql_fetch_assoc(mysql_query("SELECT look, username FROM users WHERE id = '$id'"));
    echo $getusers['username'];
    echo '<br />';
}

For sub query you can try,

SELECT look, username FROM users
WHERE id IN 
       (SELECT userId FROM group_memberships
        WHERE groupid = $id
        LIMIT 10)

Using JOIN,

SELECT u.look,u.username
FROM users as u
LEFT JOIN group_memberships as gm
     on gm.userId = u.id 
     WHERE gm.groupid = $id
     LIMIT 10 

Note: Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn about prepared statements instead, and use PDO, or MySQLi - this article will help you decide which. If you choose PDO, here is a good tutorial.