What MySQL Returns with Time Components in DATEDIFF Function

MySQL DATEDIFF() function also works with date and time values but it ignores the time value. Hence even if we include the time value in DATEDIFF() function MySQL will return the difference, in days, between dates by ignoring the time values.

mysql> Select DATEDIFF('2018-10-22 04:05:36','2017-10-22 03:05:45');
+-------------------------------------------------------+
| DATEDIFF('2018-10-22 04:05:36','2017-10-22 03:05:45') |
+-------------------------------------------------------+
|                                                   365 |
+-------------------------------------------------------+
1 row in set (0.00 sec)

mysql> Select DATEDIFF('2017-10-22 04:05:36','2017-10-22 03:05:45');
+-------------------------------------------------------+
| DATEDIFF('2017-10-22 04:05:36','2017-10-22 03:05:45') |
+-------------------------------------------------------+
|                                                     0 |
+-------------------------------------------------------+
1 row in set (0.00 sec)

The queries above shows how DATEDIFF() function ignores the time value while calculating the difference between dates.