Calculate Difference in Time with PHP

Howdy folks! :)

I've been working on a new project that calculates hours worked. I need to take up to three 24hr clock IN and clock OUT entries stored in MySQL and come up with a calculated sum difference in time.

I've seen lots of examples from folks via Google searches, but I'm stuck. I can't seem to get the the calculations right.

I am storing up to a possible 3 entries per/work day. Below is my weak attempt to get started...

$query = "SELECT * FROM emphours

        WHERE `Date` BETWEEN '".$_POST['Start']."' and '".$_POST['End']."'";



    $time1=$row["Out1"]-$row["In1"]; 

    $ext1 = "$time1:";



    $time2=$row["Out2"]-$row["In2"]; 

    $ext2 = "$time2:";



    $time3=$row["Out3"]-$row["In3"]; 

    $ext3 = "$time3:";



    $ExtTot = $ext1 + $ext2 + $ext2;

I found a web tool that is an outstanding example of what I'm trying to accomplish, except I need to make some modifications to suit my exact requirements... I'm attempting to contact the author/website owner to gain some insight.

timesheet.php

The scripting this site has is right on target.

Any tips, pointers, suggestions would be greatly appreciated.


Tom