mismatch_product_num.sql

SELECT id,
       name,
       num_prod,
       vendor_product_count
FROM
  (SELECT vendor_id,
          count(*) AS num_prod
   FROM products
   GROUP BY vendor_id) foo
RIGHT JOIN
  (SELECT id,
          name,
          vendor_product_count
   FROM vendors) bar ON foo.vendor_id = bar.id
WHERE COALESCE(num_prod, 0) != vendor_product_count