SQL statment & dates

[Unquick]

I having problems creating a statment that will update a feild by a number of days. 😕

I.E.

UPDATE users SET user_expirydate = user_expirydate + 15 days

can MySQL even do this? I know it works on the ISeries, but who the phuck knows about mysql. =)

[Pig]

do it with php and strtotime().

UPDATE table SET field_name='" . strtotime("$date + 15 days") . "...