How do i make a field value expire?

[fluppet]

Hi, im wanting a script/query to be executed every 12 hours, or alternatively when the user logs in, if it hasnt been executed in the last 12 hours, for it to be executed. How do i do this?

I have a huge book on PHP4, but i cant find anything appropriate. I didnt think i could use a session, as surely a 12 hour session si too long, and that the sessoin would expire when the user leaves etc.

I was thinking of changing a value in an sql database to 1 when the user has had the script executed, and perhaps making it only valid for 12 hours. Is this possible?

Or could i use some sort of javascript or something?

Thanks, Fluppet.

[kemu_]

You could store the timestamp when the script has been last excuted (e.g to the db). You can get this with time()-function. And next time when the user enters, you get that timestamp from the db (or wherever) and compare it to the current timestamp. If the difference is over 43200 (12 60 60 ), then execute the script again.

Depending on you host, you might also use something like crontab/task scheduler to schedule executing of certain scripts.