Question: Return ids of all the products that are supplied by supplier id 2 and are more expensive than the average price of all products.
SQL: SELECT T1.product_id FROM product_suppliers AS T1 JOIN products AS T2 ON T1.product_id  =  T2.product_id WHERE T1.supplier_id  =  2 AND T2.product_price  >  (SELECT avg(product_price) FROM products)