<?php
    // get all of the ids for a user
    $result = mysql_query("SELECT id FROM tbl_gallery WHERE fld_userid = $UserID");
    
    // get the number of rows returned
    $numrows = mysql_num_rows($result);
    
    //build an array of the ids returned
    $idarr = array();
    
    while ($row = mysql_fetch_assoc($result))
    {
        $idarr[] = $row(id);
    }

    // build an array with 4 randomly selected ids in it
    $selidarr = array();
    
    for ($i=0;$i<=4;$i++)
    {
        $selidarr[] = $idarr[rand(0,$numrows)];
    }
    
    //convert the array into a string for use in a query
    $selidstr = implode(",", $selidarr);
    
    // run one more query to get the final desired results
    $sql = "SELECT * FROM tbl_gallery WHERE $id IN ($selidstr)"
?>