MySQL - add zeroes to a time based query where no result found

Question

I have a query that prints out times and averages. The only problem is - if nothing happened in the time period of the 6 weeks that I'm running this for - it skips right over it... I need that 15 minute period to have a NULL or zero in its place. Here is my Query:

$staffing_qry = "SELECT MAKETIME(hour(opened_dt),floor(minute(opened_dt)/15)*15,0) AS time, ";
$staffing_qry .= "ROUND(COUNT(*)/COUNT(DISTINCT DATE(opened_dt)),1) AS calls, ";
$staffing_qry .= "ROUND(AVG(work_time)/60,1) AS work, ";
$staffing_qry .= "ROUND(AVG(tele_time)/60,1) AS tele, ";
$staffing_qry .= "ROUND(AVG(comm_time)/60,1) AS comm, ";
$staffing_qry .= "ROUND(IFNULL(COUNT(*)/COUNT(DISTINCT DATE(opened_dt)),0)/3,1) AS techs ";
$staffing_qry .= "FROM detail_head ";
$staffing_qry .= "LEFT JOIN detail_detail ON detail_detail.detail_head_uid = detail_head.detail_head_uid ";
$staffing_qry .= "WHERE dayname(opened_dt) = $dow_option $staffing_option $proactive_option $incoming_option ";
$staffing_qry .= "AND (DATE(opened_dt) >= (CURDATE() - INTERVAL 42 DAY))";
$staffing_qry .= "GROUP BY (hour(opened_dt)*100)+floor(minute(opened_dt)/15) ";

Suggestions?

Answer 1

RESOLVED:

if(isset($_REQUEST['date_range'])) {
        $date_range_option = (integer) $_REQUEST['date_range'];
}