(mysql) Resetting a custom profile field if user is not online (via cron)

[rootnik]

I know, this is a very strange request for help.

I need some help putting this all together...

I know the time stamp for whoseonline:
$datecut = TIMENOW - $vbulletin->options['cookietimeout'];

The time stamp for last activity is in user.lastactivity

The profile field is in userfield.field10

field10 is a drop downbox. There are only 3 vaules:

1. null
2. Closed
3. Open

What I want to do is IF the user has field10 set to "Open", change it to "Closed" if they are not currently active. This will be done via a cron job every 45 minutes.

The most efficent way would be:

Check the database for user ids (userfield.userid) who has field10 set to "Open".

Then check to see if those users are online(by comparing $datecut with user.lastactivity). If they are not, set field10 to "Closed"

Anybody up to helping a mysql dummy out? :(



Edit:


I know how to query the database for a list of userids that have field10 set to closed...


SELECT `userfield`.`userid`
FROM userfield
WHERE (
`userfield`.`field10` = 'Closed'
)


And how to find a list of users who are no online


SELECT `user`.`userid`, `user`.`lastactivity`
FROM user
WHERE (`user`.`lastactivity` < $datecut)


But I am having a very hard time connecting the 2 together. I need to somehow match the userid in the userfield table with the userid in the user table and then get the lastactivity.

As you can see, I am lost (but trying)