CREATE ALGORITHM =  TEMPTABLE VIEW  payment_state AS (
SELECT
   payment_personID,
 CASE
   WHEN IFNULL(paid,0) < IFNULL(due,0) AND due <> 0 THEN 'under'
   WHEN IFNULL(paid,0) > IFNULL(due,0) THEN 'over'
   WHEN IFNULL(paid,0) = IFNULL(due,0) THEN 'equal'
   END AS state
FROM payments);