Question

我在名称栏中有一个表Customers和一个表Salesman：

    Table Customers              Salesman Table
   --name--                           --name--
    Peter                              Charlie
    Vlado                              Clint
    Landon                             Tim
                                       Armand

如果我使用此查询：

select a.name as CustomerName, b.name as SalesmanName from Customers a, Salesman b

然后我明白了：

CustomerName        SalesmanName
Peter                Charlie
Vlado                Charlie
Landon               Charlie
Peter                Clint
Vlado                Clint
Landon               Clint
Peter                Tim
Vlado                Tim
Landon               Tim
Peter                Armand
Vlado                Armand
Landon               Armand

但想要得到的是：

CustomerName          SalesmanName
Peter                   Charlie
Vlado                    Clint
Landon                    Tim
                        Armand

我该怎么办？是否可以使用查询将这些列与它们在表中的列完全相同？

Answer 1

您可以使用ROW_NUMBER()函数生成一个对加入两者有用的任意行号：

;with cust AS (select name,ROW_NUMBER() OVER(ORDER BY name) AS RN from Customers)
     ,sales AS (select name,ROW_NUMBER() OVER(ORDER BY name) AS RN from Salesman)
select a.name as CustomerName
     , b.name as SalesmanName 
from cust a
FULL JOIN sales b
  ON a.RN = b.RN
ORDER BY COALESCE(a.RN,b.RN)

Answer 2

我假设您的表中有主键，然后您可以使用 ROW_NUMBER 和 FULL OUTER JOIN 配对这两列。假设vim:tw=78:ts=2:sw=2:expandtab:ft=help:norl:和CustomerId分别是SalesmanId和Customers表的主键。现在，这是查询： -

Salesman

这是结果

SELECT 
     ISNULL(CS.Name, '') AS CustomerName,
     ISNULL(SM.Name, '') AS SalesmanName
FROM
(
    SELECT
        Name,
        ROW_NUMBER() OVER (ORDER BY CustomerId) AS RN
    FROM Customers
) CS
FULL OUTER JOIN 
(
    SELECT
       Name,
       ROW_NUMBER() OVER (ORDER BY SalesmanId) AS RN
    FROM Salesman
) SM
ON SM.RN = CS.RN

从不同的表中获取原始数据

2 个答案: