Dates and showing for different GMT timezones

[mdowling]

On my site users can enter in comments and the comment has a date attached to it. Is there a way that I can have users set their GMT timezone difference (+0200 for example) and show the date in my database for that comment adjusted for that user?

[Drakla]

When they enter the data, or when it's displayed?

The latter would be more flexible as you're always entering a fixed scale timestamp, and either a field in a user's account, or a cookie you could set for them after asking them their timezone could then be used to adjust it on output.

[mdowling]

When it's displayed.

I would store the user's timezone in my database, and when they view any dates, how could I adjust it?

When dates are entered into my database right now, I just use the regular date. So I guess I would have to take the user's GMT offset and convert that the person looking at the date's GMT offset. Is there some kind of PHP function for this?

[Drakla]

You could store their offset as plus and minus hours, then use [man]gmdate[/man] with the timestamp of your date field (use UNIX_TIMSTAMP() on the field if it's not already one) then add offset * 3600

SELECT (UNIX_TIMESTAMP(thedatefield) + toffset * 3600) as tstamp FROM mytable...

then later display

gmdate('r', $row['tstamp']);