T-Sql找到重复的行值

Question

我想写一个存储过程。

在该存储过程中，我想从表中查找重复的行值，并将这些行的sum操作计算到同一个表。

假设我有CustomerSales表格;

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

我需要把桌子变成......

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

当我同时找到SalesRepresentative和Customer个重复项时，我想要将这些行的所有Quantity值相加并分配到表的第一行，其他人将会是'0'。

你能帮助我吗？

Answer 1

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包含0 的额外行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

这大量使用window functions。

没有窗口功能的替代版本：

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