update BUS_PROD_ITEM_SN b set b.ACTION_BY = (select t.ACTION_BY from BUS_PROD_SN_LOG t order by t.PRODUCT_ITEM_SN_IDX desc limit 0,1);
order by 在 limit 之前。update BUS_PROD_ITEM_SN b set b.ACTION_BY = ( select t.ACTION_BY from BUS_PROD_SN_LOG t order by t.PRODUCT_ITEM_SN_IDX desc limit 0,1 );
select t.ACTION_BY from BUS_PROD_SN_LOG t order by t.PRODUCT_ITEM_SN_IDX desc limit 0,1 );