Response Averages

[raouleduke]

I have a table that stores surveying data, when a survey is completed it is recorded with timedate, when the survey is resolved it is also timedate. I am looking to get the average between these two times. I have this to calculate the response times for each entry, but I want to get a customer average. Each customer will have many entries.

function timediff($startTime,$endTime){ 
    //you can modify what the function returns 
    global $timediff;  //global array if you need it 
    $a = strtotime($endTime) - strtotime($startTime); 
    $w = $a/3600; //hours.minutes 
    $h = floor($w); 
    $ms = $w - floor($w); 
    $ms = $ms*60;  //minutes.seconds 
    $m = floor($ms); 
    $s = number_format(($ms - $m)*60); 
    //basics, declare other parts if needing decimal portions 
    $timediff['hours']=$h; 
    $timediff['minutes']=$m; 
    $timediff['seconds']=$s; 
		if($h == '0' && $m == '0'){
		return "$s Sec"; 
		}elseif($h == '0'){
		return "$m Min"; 
		}else{
		return "$h Hrs $m Min"; 
		}

} 

print"<table border ='1' cellspacing='10'>";

$query = "SELECT * FROM call_data WHERE resolved != '0000-00-00 00:00:00' AND hotspot > '0' AND completed_date >= '2008-12-09' ORDER by dealer";
$result = mysql_query($query);
while ($row = mysql_fetch_array($result)) {
$completed_datetime = $row["completed_datetime"];
$first_response = $row["first_response"];
$first_response_user_id = $row["first_response_user_id"];
$resolved = $row["resolved"];
$resolved_user_id = $row["resolved_user_id"];
$dealer = $row["dealer"];
$hotspot = $row["hotspot"];

$time4 = timediff($completed_datetime,$first_response); 
$time5 = timediff($completed_datetime,$resolved);

if($resolved == $first_response){
$time6 = '';
}else{	
$time6 = timediff($first_response,$resolved); 
} 



		 							$query56 = "SELECT * FROM users WHERE id = '$first_response_user_id'"; 
									$result56 = mysql_query($query56);
									while ($row56 = mysql_fetch_array($result56)){
									$user_name = $row56['name'];
									}	

		print"<tr>
		<td>$dealer</td>
		<td>$user_name</td>
		<td>$time4</td>
		<td>$time5</td>
		<td>$time6</td>
		<td>$hotspot</td>
		</tr>";

}

echo"</table>";

any info would be greatly appreciated. thank you.