UPDATE SKU SET STD_COST_PRICE = T.STD_COST_PRICE,UPDATE_USER_NAME='MODIFY',USER_UPDATE_DATETIME='2024-08-31 00:00:00' 
from (
    select SKU_CODE,GOODS.STD_COST_PRICE from SKU
        join (
        select GOODS_CODE,avg(STD_COST_PRICE) as av from SKU
        group by GOODS_CODE
        ) as T1 on SKU.GOODS_CODE = T1.GOODS_CODE
    join GOODS on GOODS.GOODS_CODE = SKU.GOODS_CODE
    where GOODS.STD_COST_PRICE < T1.av
) as T
where T.SKU_CODE = SKU.SKU_CODE;