SQL syntax help

[Tryfwar]

I was hoping that somebody might be able to help me with this problem:

Firstly, I have created a new table in my forums db called userclass and in it there are 2 fields: userclassid & title.

Then i have added a field to the user table called 'userclassid' as well and have successfully been able to modify the user.php to enable me to assign a class title to each user.

In addition to this i have added a field to the usergroup table called 'rollcall' which is simply a 1 or 0, so i can assign wether or not i wish for these usergroups to appear in the rollcall. (just like the showgroups function does for the showgroups.php)

The problem i have is in this query that was originaly from the showgroups.php, i cannot work out how i should write it

I would like it so that it will list users in groups of class and only those who have been assigned '1' in the usergroup.rollcall table.

The below Query displays them almost as i want but it lists each user 5 times!! lol oh and it also seems to display users regardless of the WHERE clause :/

PHP Code:

$users = $DB_site->query("
    SELECT
        $classfieldselect userclass.title, user.userid, user.username, user.userclassid,  user.userclassid,
         user.usergroupid
        FROM userclass
        LEFT JOIN user ON (userclass.userclassid = user.userclassid)
        LEFT JOIN userfield ON (userfield.userid = user.userid)
        LEFT JOIN usergroup ON usergroup.rollcall
        WHERE usergroup.rollcall = 1
    "); 


Thanks in advance to anyone who can help