WITH CTE_AVGPRICE AS (
	SELECT
	    GOODS_CODE
		, ROUND(AVG(STD_COST_PRICE)) AS AVG_PRICE
	FROM
		SKU
	GROUP BY
		GOODS_CODE
)

UPDATE
    SKU AS TARG
SET 
    STD_COST_PRICE = GOODS.STD_COST_PRICE
FROM
    SKU
    INNER JOIN CTE_AVGPRICE ON
        SKU.STD_COST_PRICE < CTE_AVGPRICE.AVG_PRICE
    INNER JOIN GOODS ON
        SKU.GOODS_CODE = GOODS.GOODS_CODE
WHERE
    1=1
;