CREATE TABLE Products (product_name VARCHAR, product_id VARCHAR)
CREATE TABLE Order_items (product_quantity INT, product_id VARCHAR)

Show all product names and the total quantity ordered for each product name.
SELECT T2.product_name, SUM(T1.product_quantity) FROM Order_items AS T1 JOIN Products AS T2 ON T1.product_id = T2.product_id GROUP BY T2.product_name
SELECT "T2"."product_name", SUM("T1"."product_quantity") FROM "Order_items" AS "T1" JOIN "Products" AS "T2" ON "T1"."product_id" = "T2"."product_id" GROUP BY "T2"."product_name"