表一:
表二:
-- 问题,表一是总库存表,表二是销售记录表求剩余库存
SELECT
tsi.type,
(tsi.last_count - if(t.sales,
t.sales,
0)
) as remaining_invetory
from
t_shop_info tsi
left join (
SELECT
type as type_a ,
sum(sale_count) as sales
from
t_sale_info
group by
type
) t on
tsi.`type` =