PHP / MySQL的-从一个表中选择ID，除了在另一个表中的ID

Question

for example i have 2 tables:
1 . :

1       Mike
2       Adam
3       Tom
4       John
5       Andy
6       Ray

2 . :

\n \n1 ... \n3 ... \n6 ... \n

i want to make a page which can be visited once in 12 hours, when user visits that page his id is included in database ( visits ), how i can select all users ( from database ) excepting users who visited page in <= 12 hours ( users from database )?

Answer 1

First of all, you don't mean "from one database [...] which are in second database", they're just in different tables, but in the same database :)

Anywho, something like this:

SELECT * FROM users WHERE id NOT IN 
(SELECT userID FROM visits WHERE date > DATE_SUB(NOW(), INTERVAL 12 HOUR)) 

or something like that :)