UPDATE GOODS 
SET GOODS.STD_COST_PRICE = SKU.STD_COST_PRICE 
FROM GOODS 
INNER JOIN SKU 
ON GOODS.GOODS_CODE = SKU.GOODS_CODE 
WHERE SKU.STD_COST_PRICE < ROUND(AVG(SKU.STD_COST_PRICE)) 
GROUP BY GOODS_CODE;