problem in computation of lates(disregard Seconds)

[newphpcoder]

Hi..I got problem in getting the time difference between two datetimes.My problem is how can I only get the difference of hours and minutes disregard the seconds from datetime..here is my sample login and logout:Login : 2012-03-12 05:39:17Logout: 2012-03-12 13:35:16And here is my code in getting the Rendered or total hours:

UPDATE reg_att SET Rendered = casewhen time_to_sec(time(LOGIN)) BETWEEN time_to_sec('05:35:00') AND time_to_sec('06:59:00') AND time_to_sec(time(LOGOUT)) BETWEEN time_to_sec('13:35:00') AND time_to_sec('15:35:00')AND DATE_FORMAT(LOGIN, '%W') IN ('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday')then sec_to_time(time_to_sec(concat(substr(LOGIN, 1,10), ' ' , '08:00:00')) -(time_to_sec(LOGIN) - time_to_sec(concat(substr(LOGIN, 1,10), ' ' , '05:35:59'))))End;

the output of this is :Rendered = 07:56:42and I need to compute the lates:I used this code for lates:

UPDATE reg_att SET Late = casewhen time_to_sec(time(LOGIN)) BETWEEN time_to_sec('05:35:00') AND time_to_sec('06:59:00') AND time_to_sec(time(LOGOUT)) BETWEEN time_to_sec('13:35:00') AND time_to_sec('15:35:00')AND DATE_FORMAT(LOGIN, '%W') IN ('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday')then sec_to_time(time_to_sec('08:00:00') - time_to_sec(Rendered))END;

the output of this is:Late = 00:03:18Now, How can be the late become : 00:04:00Disregard the seconds?his schedule is 05:35 - 13:35he login 05:39, so he was late 4 minutes, but in my code it computes 00:03:18 because it regards the seconds.Any help is highly appreciated.Thank you so much..