各位大哥 请问这两题怎么写

求别沉

求救🆘

顶呀

顶

题1：答案：
首先：确保order、item的订单号都是唯一性的，不重复的，即一对一；
select substr(date,1,7) year_month,pid,sum(price*sl) as income
from order t1
inner join item t2
on (t1.id = t2.id)
where date between '2002-12-01' and '2012-12-31'
group by pid

需求2：
select substr(date,1,7),cusid,sum(price*sl) as income
from order t1
inner join item t2
on (t1.id = t2.id)
where date between '2002-12-01' and '2012-12-31'
group by substr(date,1,7),cusid

销售额：价格*数量；