php - Dynamic subqueries -

i have following problem. have table atr_product contains columns atr_id, product_id.

think registers are:

i send atr_id array ws in php. example have atr_ids = (1,2,3);. so, when receive these atr_ids, query should return product_id 200.

if send atr_ids = (1), query should return product_id = (200,201) easy, atr_ids dynamic, don't know how many ids ws receive.