[kh99]

I haven't tried this at all, but if I had to guess I'd say your code should be something like:

PHP Code:

// Get the value for field 
$user = $db->query_first(" 
SELECT field7 
FROM " . TABLE_PREFIX . "userfield 
WHERE userid = " . $vbulletin->userinfo['userid'] . " 
"); 

// change user groups

if ($user['field7'] == 'yes') 
    $newgroup = 23; 
else 
    $newgroup = 24;

$getusergroupid = iif($userinfo['displaygroupid'] != $userinfo['usergroupid'], $userinfo['displaygroupid'], $newgroup);

$user_usergroup =& $vbulletin->usergroupcache["$newgroup"];
$display_usergroup =& $vbulletin->usergroupcache["$getusergroupid"];
$userdata->set('usergroupid', $newgroup);
$userdata->set_usertitle(
    $user['customtitle'] ? $user['usertitle'] : '',
    false,
    $display_usergroup,
    ($user_usergroup['genericpermissions'] & $vbulletin->bf_ugp_genericpermissions['canusecustomtitle']) ? true : false,
    ($user_usergroup['genericpermissions'] & $vbulletin->bf_ugp_genericpermissions['cancontrolpanel']) ? true : false
);

if ($user['userid'] == $vbulletin->userinfo['userid'])
{
    $vbulletin->userinfo['usergroupid'] = $newgroup;
    $vbulletin->userinfo['displaygroupid'] = $newgroup;
} 


ETA: (oops - posted this before I read Lynne's. Maybe there is an existing mod).