HW 4 and 6 graded, 10/10 for both!

HW 6 6/8:

insert question- missing 'unit' condition
correct answer for Alter question:
ALTER TABLE product_units
ADD current_quantity INT;

UPDATE product_units
SET current_quantity = (
SELECT current_quantity
FROM (
SELECT p.product_id, COALESCE(quantity,0) as current_quantity

	FROM product_units p
	LEFT JOIN (
		SELECT *
		,ROW_NUMBER() OVER( PARTITION BY vi.product_id ORDER BY market_date DESC) AS rn
		FROM vendor_inventory vi 
	) vi ON p.product_id  = vi.product_id

	WHERE rn = 1 
	OR rn IS NULL
) p

WHERE product_units.product_id = p.product_id);