Simple question about calculate date

[sunnyside]

I have two date fields with different format, one is human read format: yyyy-mm-dd (2004-12-01); another one is unix time stamp.

My question is if I need to get the date that 7 days before one specific date (for example: 2004-12-08, 7 days before it would be 2004-12-01, how to do it by using these two different format of date?

For unix time stamp, just transfer day to seconds, then mines it?

thank you for your tips.

[devinemke]

regardless of what format the date is in, convert it to a UNIX timestamp (if it isn't already) then simply subtract:

$date = '2004-12-01';
echo date('Y-m-d', strtotime($date) - 604800); // outputs 2004-11-24

[onion2k]

Unix timestamps are awesome ... unless theres a chance your date will be outside of the 1970 - 2038 range.. then they'll not work.

[devinemke]

Originally posted by onion2k
Unix timestamps are awesome ... unless theres a chance your date will be outside of the 1970 - 2038 range.. then they'll not work.

i believe some OS's (not made by microsoft) support negative timestamps, therefore supporting dates prior to 1970.

[sunnyside]

Thanks, that's what I think too.