Question

Could anyone solve my problem please.
I have mysql table with time_start ‘hour:minute’ and time_end ‘hour:minute’ how can i get cumulative time duration between time_start and time_end.
thanks,

$sel = $db->query("SELECT * FROM logbook WHERE date = '$date' ");

while($sel_row = mysqli_fetch_array($sel))
{
  $duration = (strtotime($sel_row['time_end'])-strtotime($sel_row['time_start']))/(60*60);        
  $hour = floor($duration);
  $minute = ($duration - $hour)*60;
  echo $hour.":".$minute;
  ? HERE HOW CAN I CUMULATE THE $hour:$minute       
}

Answer 1

Do the summation where you calculate the duration

$duration = 0;
while($sel_row = mysqli_fetch_array($sel))
{
  $duration += (strtotime($sel_row['time_end'])-strtotime($sel_row['time_start']))/(60*60);        
}
$hour = floor($duration);
$minute = ($duration - $hour)*60;
echo $hour.":".$minute;

Or better, let MySQL do the calculation:

SELECT (SUM(time_end) - SUM(time_start)) / 3600 FROM logbook WHERE date = '$date';