题解 | #牛客的课程订单分析(一)#

select id,name,weight,total from goods ,
(select t.goods_id , sum(t.count) as total from trans t group by t.goods_id) ts
where goods.id = ts.goods_id
and (goods.weight<50 and ts.total > 20)

简简单单，照着条件写就行