How to subtract hours from a datetime in MySQL?

Question

I get a datetime field, that's currently in the query as:

SELECT DATE_FORMAT(x.date_entered, '%Y-%m-%d') AS date FROM x ORDER BY date ASC 

What I want to do is to subtract 3 hours from that date (GMT issues), but I can't do it in PHP as PHP only knows the date part, not the time.

Answer 1

mySQL has DATE_SUB():

SELECT DATE_SUB(column, INTERVAL 3 HOUR).... 

but would it not be better to try and sort out the underlying time zone issue instead?

Answer 2

Assuming you have some timezone issue and know source and destination timezone, you could convert it like so

SELECT DATE_FORMAT(CONVERT_TZ(x.date_entered, 'UTC', 'Europe/Berlin'),                    '%Y-%m-%d') AS date FROM x ORDER BY date ASC;