mysql change time in radcheck table

I am using freeradius with mysql. Thousands of users account expiration is stored in radcheck table. Expiration value is as follows 29 Jul 2018 12:00:00 30 Jul 2018 12:00:00 I want to change only 12:00:00 to 00:00:00 (means date remains same for each user but time should change to 00:00:00) so that it will look alike 29 Jul 2018 00:00:00 30 Jul 2018 00:00:00 Regards, J <http:///>