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mysql> SELECT login_time, logout_time FROM login; +---------------------+---------------------+ | login_time | logout_time | +---------------------+---------------------+ | 2020-03-09 09:15:00 | 2020-03-09 15:00:00 | | 2020-03-10 09:30:00 | 2020-03-10 16:00:00 | | 2020-03-11 09:00:00 | 2020-03-11 13:30:00 | +---------------------+---------------------+ 3 rows in set (0.00 sec) mysql> SELECT sec_to_time(SUM(timestampdiff(SECOND, login_time, logout_time))) as total -> FROM login; +----------+ | total | +----------+ | 16:45:00 | +----------+

Sounds like you are comparing datetimes against date only values, in which case you need to compare just the date portions of the datetime values ... WHERE DATE(ClockingInDate) <= '$edate1' AND DATE(ClockingOutDate) >= '$sdate1'

Remember what I said about using a form? Use a form.

Why are you even attempting to store that duration. You can get it any time you need it with a query. Rule of DB design - don't store derived data. If you really insist on storing it, why do need two queries? UPDATE attendance_records SET duration = timediff(...) WHERE ... - a single update would do the job