group by的使用

1.按照Customer分组，列出每个Customer的OrderPrice

select Customer,SUM(OrderPrice) from Orders
 group by Customer

 

2.按照creator把每个creator的cost_price列出来

select  sum(m.cost_price) num from scm_product m group by m.creator

 

3.按照creator把每个creator的cost_price列出来并且按照cost_price倒序排序

  select *
   from (select sum(m.cost_price) num from scm_product m group by m.creator) result
  order by result.num desc