如何从 MySQL 中的日期时间中减去小时数？

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;

Answer 3

Normal select query.

Once applied DATE_ADD() function in MySQL

select lastname, 
    date_add(changedat, interval -24 hour) as newdate
from employee_audit;

lastname and changedat is field name and employee_audit is table name.