如何按团队按月查询销售总额？

Question

当我有这样的桌子时，每月获得最佳销售团队的最佳方法是什么：

结果应该是这样的（按订单总价分组）：

Month | Team | Sales
____________________
March |   2  | 3453 
April |   3  | 1353 
May   |   2  | 5341

我之前已经加入了两个表，但是由于某种原因，加入4个表并按月分组似乎很困难。 谢谢。

Answer 1

这应该做到。我也加了一年。它使用CTE

with cte as
(
    select Team_nr, sum(price) as Sales, date_part('month', Created) as _Month, date_part('year', Created) as _Year
    from employee e 
    inner join orders o on e.id = o.employee_ID
    inner join products p on p.id = orders.product_id 
    Group by Team_nr, date_part('month', Created), date_part('year', Created)
)
select Team_nr, Sales, _Month, _Year
from cte a
where not exists(select 1 from cte b where 
a._Month = b._Month and a._Year = b._Year and a.Team_nr <> b.Team_nr and a.Sales < b.Sales  )

Answer 2

在Postgres中，您可以使用distinct on －如果您每月只需要一行：

select date_trunc('month', created), e.Team_nr, sum(p.price) as Sales
from employee e  join
     orders o
     on e.id = o.employee_ID join
     products p
     on p.id = orders.product_id 
group by e.Team_nr, date_trunc('month', o.Created)
order by date_trunc('month', o.Created), sum(p.price) desc