How exactly does using OR in a MySQL statement differ with/without parentheses?

Question

I have this query:

SELECT * FROM (`users`) WHERE `date_next_payment` <= \'2011-02-02\' 
    AND `status` = \'active\' OR `status` = \'past due\'
         


        

Answer 1

In your first query status = 'active' is condition false then not evalute next status column condition(status )

in Your second query

parentheses () have high priority

. So (status = 'active' OR status = 'past due') condition evaluate first.