These both correctly return the current UNIX timestamp:
SELECT UNIX_TIMESTAMP(LOCALTIMESTAMP()); #MySql
echo time(); //PHP
But I'm storing UTC_TIMESTAMPs in my database (not LOCALTIMESTAMPs).
How can I convert a UTC datetime to a UNIX timestamp using MySQL?
Note that LOCALTIMESTAMP() is a synonym for NOW(). So what you're really asking is how to get the current time and convert it to GMT and then convert to a unix timestamp to store in the db. So this will work:
SELECT UNIX_TIMESTAMP(CONVERT_TZ(NOW(), @@global.time_zone, 'GMT'));
As an aside, it's always much better to use the time and date columns of a database rather than unix timestamps. It makes querying and displaying results much easier.
Update: Are you sure you are getting what you think you are? UNIX_TIMESTAMP returns a UTC based seconds since the UNIX epoch. It does not return a MySQL DateTime type. If you have an actual UTC DateTime instance, then you can put that directly into your DateTime column of your database and don't have to use UNIX_TIMESTAMP as an intermediary. What type do you actually have that's in local time?
