SELECT count(*) ,  T2.product_id FROM problems AS T1 JOIN product AS T2 ON T1.product_id = T2.product_id GROUP BY T2.product_id
For each product which has problems, what are the number of problems and the product id?
SELECT count ( * ) , T2.product_id FROM problems AS T1 JOIN product AS T2 ON T1.product_id = T2.product_id GROUP BY T2.product_id
select count ( * ) , t2 . product_id from problems as t1 join product as t2 on t1 . product_id = t2 . product_id group by t2 . product_id
For each product which has problems , what are the number of problems and the product id ?