maths help

[EchoFool]

Hey,

 

Im trying to get my script to work out average time of completion over a range of start and end times of tasks but the result using the AVG function gives a number on huge values because im using time stamps so have no idea how to get it in the format of:

 

Days : Houses : Minutes : Seconds

 

How ever at moment i keep getting results like:

UserID 4

Total 58

Average 19388391265527

 

Its the average thats incorrect

 

This is what i have:

<?php
$GET = mysql_query("SELECT Count(MissionID) AS Total,AVG((CompletedOn-StartedOn)) AS AverageTime,UserID FROM tasktime WHERE Complete='2' GROUP BY UserID ORDER BY Total DESC,AverageTime DESC LIMIT 20")
Or die(mysql_error());


While($row = mysql_fetch_assoc($GET)){
Echo 'UserID '.$row['UserID'];
Echo '<br>';
Echo 'Total '.$row['Total'];
Echo '<br>';
Echo 'Average '.$row['AverageTime'];
?>

 

Any chance can point me in right direction