Query to reset join date of all users?

[Spank]

What is says on the tin. Is there a query I can run to set the join date of all users to a specific date? I want this because I bought the site from somebody else who was running it on myBB, so I impexed all the users to vbulletin, they have their original join date, I would like to reset these to the date I transferred them.

[Dismounted]

UPDATE user
SET joindate = X
Where "X" is the date, in seconds after UNIX epoch ("UNIX time").

[Spank]

Cheers very much, Dismounted.