Question

I would like to compare two tables and then update if some logic is true,

In pseudo code:

SELECT * FROM users, usersold IF users.id=usersold.id THEN UPDATE users.status=1; 

Is there a way to do it in MySQL?

Answer 1

UPDATE users u SET status = 1 WHERE EXISTS (SELECT id FROM usersold WHERE id = u.id) 

Alternate version:

UPDATE users SET status = 1 WHERE id IN (SELECT id FROM usersold) 

You should test and, depending on your database, you may find one performs better than the other although I expect any decent database will optimize then to be much the same anyway.