Question

i have a Mysql table shift_def in the following format.

+-------------------------------------------------------------------------------+
|  id   |   name   |   start_time   |    end_time   |   description   |  break  |
|-------------------------------------------------------------------------------|
|  101  | Shift1   |    01:03:55    |    06:00:55   |  Shift 1        |   1     |
|-------------------------------------------------------------------------------|
|  102  | Shift2   |    06:03:55    |    01:00:55   |  Shift 2        |   3     |
+-------------------------------------------------------------------------------+

to find the total shift duration. i perform the following process in my php.

$shift_time = mysql_query("select start_time, end_time from rpt_shift_def where name ='Shif1'")or die(mysql_error());
        while ($row = mysql_fetch_assoc($shift_time)) 
        {
           $Total_shift_time = strtotime($row['end_time']) - strtotime($row['start_time']);
            $hours=floor($Total_shift_time/3600);
            $Total_shift_time-=$hours*3600;
            $minutes=floor($Total_shift_time/60);
            $Total_shift_time-=$minutes*60;
            $seconds=$Total_shift_time;
            $Total_shift_time=$hours.":".$minutes.":".$seconds;*/                                                                                                                                                                                                                                                                                                                                                                            
            echo "$Total_shift_time";
            echo "</br>";
        }

the output is

4:57:0

when i try the same for shift 2 the expected output is

18:57:0

but the output is

-6:57:0

the negative value is because end_time of the shift 2 is less than start_time.
how to solve this problem.

can anyone help me out.

Answer 1

If end time is less than start time, add 24 hours (the reason being that the shift ended on the following day).

Since you have already calculated $Total_shift_time, you can just check if that is negative.

if( $Total_shift_time < 0 ) {
    $Total_shift_time += 86400;  // Number of seconds in a day
}

Err… Make sure you do this after you first calculate the shift time and before you start calculating hours, minutes and seconds…