Validating Timestamp overlaps with PHP

Question

Hello all. My database holds date, start and end variables. In my code I grab the start and them as the user selects them, and convert them to timestamps like so (all inside a foreach loop)..

$selectionDate    = strtotime($timeQry['date']);
$startTimes[]       = strtotime($timeQry['start'],$selectionDate);
$endTimes[]         = strtotime($timeQry['end'],$selectionDate);

This gives me the correct start and end times as timestamps. I then have a logic statement to validate it and see if any of the selected times overlap....

if(($startTimes[1] < $startTimes[0]) && ($endTimes[1] > $startTimes[0]) ||
($startTimes[1] > $startTimes[0]) && ($startTimes[1] < $endTimes[0]) )
{   
    echo "overlap"
}

This works fine most of the time, however if one of the end times if after 12 midnight (say 02:00am), then that time stamp will be smaller than the start time because the code uses the date the booking would start on. This causes the logic to fail and the overlap is missed.

I have thought about doing:

if( ($endTimes[$k] >= $selectionDate) )
{
 $endTimes[]  = strtotime($timeQry['end'],$newDate+ 1253574000);
}
else
{
 $endTimes[]  = strtotime($timeQry['end'],$selectionDate);
}

    //...run same logic query

Which creates a new date which is a day later. But I don't think this is the right way to go about it. If anyone can help me out I would be most grateful. It's got me scratching my head a bit this one! Many thanks

Answer 1

Why don't use DATETIME for both columns, avoiding any juggling.

Answer 2

I think you almost got it, but this may be a nicer approach:

while(/* iterate */) {
    //...
    $selectionDate = strtotime($timeQry['date']);
    $startTime  = strtotime($timeQry['start'], $selectionDate);
    $endTime    = strtotime($timeQry['end'], $selectionDate);
    if($endTime < $startTime) {
        $endTime += 86400;
    }
    $startTimes[] = $startTime;
    $endTimes[]   = $endTime;
}

But as cemkalyoncu mentioned you should use two independent timestamps, instead of three "half" ones. I don't know your application, but using two complete timestamps will also cover cases where the time difference is more than 24 hours. This won't work with your current setup.