Update only Time in a mysql DateTime field

Question

How can I update only the time in an already existing DateTime field in MySQL? I want the date to stay the same.

Answer 1

This what helped me. I convert time to minutes firstly: 150 for 2:30 am.

UPDATE lesson SET starts_at = DATE_ADD(Date(starts_at), INTERVAL 150 MINUTE)

Minutes are enough accurate for me, though you can use other units: https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-add

Answer 2

I used ADDTIME in the following way

Earlier in my cloud server, the DateTime was set to UTC but after changing the DateTime to Asia/Kolkata ie UTC 5:30 I wanted the same to reflect in my database tables.

I wanted to update the created_at and updated_at column by 5 hours 30 minutes. I did the following

To update all the rows of the table

UPDATE 
    products 
SET 
    created_at = ADDTIME(created_at, '5:30:0'), 
    updated_at = ADDTIME(updated_at, '5:30:0') 

You can omit the WHERE condition if you want to update all the records, but since my new records were updated with proper values. So only my rows below id less than 2500 must be updated

UPDATE 
    products 
SET 
    created_at = ADDTIME(created_at, '5:30:0'), 
    updated_at = ADDTIME(updated_at, '5:30:0') 
WHERE
    id < 2500;

Answer 3

Try this:

UPDATE t1 SET DateTimeField = CONCAT(DATE(DateTimeField),' 12:34:56');

Answer 4

Try this:

UPDATE sms 
SET entry_period_end_date= entry_period_end_date+INTERVAL 6 Hour 
WHERE TIME(entry_period_end_date) = '06:00:00';

Answer 5

MySQL DEV page shows functions like subtime and difftime

A sample code to back the time all posts in 3 hours is above:

UPDATE tablepost SET datepost = SUBTIME( datepost , '0 3:0:0' );

Note that values 0 dont alter the respective field. Take care this code, use select first to test these function.

Reference: http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_subtime

Answer 6

Well, exactly what you are asking for is not possible. The date and time components can't be updated separately, so you have to calculate the new DateTime value from the existing one so that you can replace the whole value.