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

The MySQL manual has a page on operator precedence. It shows that AND has a higher precedence. So p1 AND p2 OR p3 is interpreted as (p1 AND p2) OR p3. A truth table will easily convince you that this is different from p1 AND (p2 OR p3).