CREATE TABLE customer_orders (order_id VARCHAR2, order_date NUMBER)
CREATE TABLE order_items (order_quantity NUMBER, order_id VARCHAR2)

Find the total amount of products ordered before 2018-03-17 07:13:53.
SELECT SUM(t2.order_quantity) FROM customer_orders AS t1 JOIN order_items AS t2 ON t1.order_id = t2.order_id WHERE t1.order_date < "2018-03-17 07:13:53"
SELECT SUM("t2"."order_quantity") FROM "customer_orders" "t1" JOIN "order_items" "t2" ON "t1"."order_id" = "t2"."order_id" WHERE "2018-03-17 07:13:53" > "t1"."order_date"