Question

您好我想从Northwind数据库中选择订购此类产品的客户的名称，例如巴西客户。我在这里做了巴西产品：

select [ProductName] 
from [dbo].[Products] join [dbo].[Order Details] on [dbo].[Products].ProductID = [dbo].[Order Details].ProductID
join [dbo].[Orders] on [dbo].[Order Details].OrderID = [dbo].[Orders].OrderID
join [dbo].[Customers] on [dbo].[Orders].CustomerID = [dbo].[Customers].CustomerID
where [Country] = 'Brazil'

但是现在呢？我怎么能找到它们？我试着这样做：

select [CompanyName], [ProductName]
from [dbo].[Customers] join [dbo].[Orders] on [dbo].[Orders].CustomerID = [dbo].[Customers].CustomerID 
join [dbo].[Order Details] on [dbo].[Order Details].OrderID = [dbo].[Orders].OrderID
join [dbo].[Products] on [dbo].[Products].ProductID = [dbo].[Order Details].ProductID
where  [ProductName] in  (
select [ProductName] 
from [dbo].[Products] join [dbo].[Order Details] on [dbo].[Products].ProductID = [dbo].[Order Details].ProductID
join [dbo].[Orders] on [dbo].[Order Details].OrderID = [dbo].[Orders].OrderID
join [dbo].[Customers] on [dbo].[Orders].CustomerID = [dbo].[Customers].CustomerID
where [Country] = 'Brazil')

但这也行不通：/

Answer 1

由于CompanyName位于原始查询的Customer表中，因此只需从那里选择它即可。

select
    [CompanyName]
  , [ProductName]
from
    [dbo].[Products]
    join
        [dbo].[Order Details]
        on
            [dbo].[Products].ProductID = [dbo].[Order Details].ProductID
    join
        [dbo].[Orders]
        on
            [dbo].[Order Details].OrderID = [dbo].[Orders].OrderID
    join
        [dbo].[Customers]
        on
            [dbo].[Orders].CustomerID = [dbo].[Customers].CustomerID
where
    [Country] = 'Brazil'

Answer 2

如果我理解你的问题（措辞不清楚），你需要做的只是将[Customer]添加到select语句中，而不是运行嵌套查询。您的问题要求选择客户的名称，因此它是select [Customer]，而不是[Company], [Product]。

希望有所帮助。

Answer 3

您理解架构错误。来自巴西的产品需要检查供应商

  SELECT ProductID
  FROM Products P
  JOIN Suppliers S
    ON P.SupplierID = S.SupplierID
  WHERE S.Country = 'Brazil'

然后客户购买巴西产品

 SELECT DISTINCT C.CustomerID
 FROM Customer C
 JOIN Orders O
   ON C.CustomerID = O.CustomerID
 JOIN OrderDetails OD
   ON O.OrderID = OD.OrderID
 WHERE OD.ProductID IN ( SELECT ProductID
                         FROM Products P
                         JOIN Suppliers S
                           ON P.SupplierID = S.SupplierID
                         WHERE S.Country = 'Brazil')

MSSQL选择具有相同产品的客户

3 个答案: