国家间贸易差额 - Northwind 数据库

Question

我有很多任务要做，使用旧的 Northwind 数据库，我需要为每个国家/地区创建一个贸易余额。这意味着，我需要计算每个国家向每个国家销售了多少，他们购买了多少以及余额是多少，正负。我有一个包含“CountryID, CountryName, ContinentID”列的 table Countries。我更希望国家以其原始名称命名，而不是 CountryID.

我有 table Suppliers 列 SupplierID 匹配 CountryId。 Customers table、CustomerID 和 CountryId.

也是如此

到目前为止我有这个：

SELECT c.CountryID, SUM(CONVERT(money, (od.UnitPrice * od.Quantity) * (1 - od.Discount) / 100) * 100) AS ProductSales
From Countries c
LEFT OUTER JOIN Suppliers s ON c.CountryID = s.CountryID
JOIN Customers cu ON c.CountryID = cu.CountryID
JOIN Products p ON s.SupplierID = p.SupplierID
JOIN Orders o ON cu.CustomerID = o.CustomerID
JOIN [Order Details] od ON o.OrderID = od.OrderID
GROUP BY c.CountryID

结果：

9   2072561.58
6   65322.04
7   56430.15
4   106925.77
19  412799.24
13  17205.45
5   200785.20
16  35966.40
17  272475.70
11  78850.80
20  2947015.56
8   406791.55

我认为它没有给我任何接近我需要的东西，可能这只是所有已售产品的价值。我坚持执行此任务，我会提供您需要的任何信息。

Answer 1

它将如下所示（抱歉，我的本地机器上没有安装此数据库）。可能会有帮助-

select
    fc.Countryname as FromCountryName,
    tc.Countryname as ToCountryName,
    SUM(CONVERT(money, (od.UnitPrice * od.Quantity) * (1 - od.Discount) / 100) * 100)
from Suppliers as s
inner join Countries as fc on fc.id = s.countryid
inner join Products as p on p.supplierid = s.id
inner join [Order Details] as od on od.productid = p.id
inner join Orders as o on o.id = od.OrderId
inner join Customers as cu on cu.id = o.customerId
inner join Countries as tc on tc.id = cu.countryid
group by fc.Countryname, tc.Countryname

我们有 Group By FromCountry 和 ToCountry 的数据。

对于下面评论的第二个要求（也许下面的查询在性能方面效率不高）-

select
    max(fc.name) as CountryA,
    min(tc.name) as CountryB,
    BalanceAB = sum(case when fc.name > tc.name then (CONVERT(money, (od.UnitPrice * od.Quantity) * (1 - od.Discount) / 100) * 100) end),
    BalanceBA = sum(case when fc.name < tc.name then (CONVERT(money, (od.UnitPrice * od.Quantity) * (1 - od.Discount) / 100) * 100) end),
    SUM((case when fc.name < tc.name then -1 else 1 end) * CONVERT(money, (od.UnitPrice * od.Quantity) * (1 - od.Discount) / 100) * 100) as [Total(A - B)]
from @Supplier as s
inner join @Country as fc on fc.id = s.countryid
inner join @Product as p on p.supplierid = s.id
inner join @OrderDetail as od on od.productid = p.id
inner join @Order as o on o.id = od.OrderId
inner join @Customer as cu on cu.id = o.customerId
inner join @Country as tc on tc.id = cu.countryid
group by (case when fc.name < tc.name then fc.name+' to '+tc.name else tc.name+' to '+fc.name end)

输出-

CountryA    CountryB    BalanceAB   BalanceBA   Total(A - B)
US          UK          20.00       200.00      -180.00

国家间贸易差额 - Northwind 数据库

Trading balance between countries - Northwind database

sql

sql-server

northwind