T-Sql 查找重复的行值

Question

我想写一个存储过程。

在那个存储过程中，我想从一个表中找到重复的行值，并将这些行的求和运算计算到同一个表中。

假设我有一个CustomerSales 表；

ID  SalesRepresentative Customer  Quantity 
1   Michael             CustA        55     
2   Michael             CustA        10

我需要把桌子转过来……

ID  SalesRepresentative Customer  Quantity 
1   Michael             CustA        65     
2   Michael             CustA        0

当我同时发现SalesRepresentative 和Customer 重复时，我想将这些行的所有Quantity 值相加并分配给表格的第一行，其他的将为'0'。

你能帮帮我吗？

Answer 1

要将重复项聚合到一行：

SELECT min(ID) AS ID, SalesRepresentative, Customer
      ,sum(Quantity) AS Quantity
FROM   CustomerSales 
GROUP  BY SalesRepresentative, Customer
ORDER  BY min(ID)

或者，如果您确实希望结果中带有0 的那些额外行作为Quantity：

SELECT ID, SalesRepresentative, Customer
      ,CASE 
          WHEN (count(*) OVER (PARTITION BY SalesRepresentative,Customer)) = 1
             THEN Quantity
          WHEN (row_number() OVER (PARTITION BY SalesRepresentative,Customer
                                   ORDER BY ID)) = 1 
             THEN sum(Quantity) OVER (PARTITION BY SalesRepresentative,Customer)
          ELSE 0
       END AS Quantity
FROM   CustomerSales
ORDER  BY ID

这会大量使用window functions。

没有窗口函数的替代版本：

SELECT min(ID) AS ID, SalesRepresentative, Customer, sum(Quantity) AS Quantity
FROM   CustomerSales 
GROUP  BY SalesRepresentative, Customer

UNION ALL 
SELECT ID, SalesRepresentative, Customer, 0 AS Quantity
FROM   CustomerSales c
GROUP  BY SalesRepresentative, Customer
LEFT   JOIN (
    SELECT min(ID) AS ID
    FROM   CustomerSales 
    GROUP  BY SalesRepresentative, Customer
   ) x ON (x.ID = c.ID)
WHERE  x.ID IS NULL
ORDER  BY ID