sql - SQL Server 分组问题

Question

我有两张桌子。

1. Customer ID, NAME, MonthlyIncome
2. Orders ID, CustomerKey, TotalCost

我想把这两张桌子合二为一，就像在商店里买的总金额一样。

CustomerKey, MonthlyIncome, TotalCost.

我试图按 分组CustomerKey，但我无法包括其余的列。我应该使用哪个查询？

SELECT 
    fs.CustomerKey, SUM(fs.TotalCost) as TotalBought
FROM 
    FactOnlineSales fs
INNER JOIN 
    DimCustomer c on c.CustomerKey = fs.CustomerKey
GROUP BY 
    fs.CustomerKey

Answer 1

我尝试按 CustomerKey 分组，但无法管理如何包含其余列。

就这样做：

SELECT fs.CustomerKey,
       c.MonthlyIncome,
       SUM(fs.TotalCost) as TotalBought
  FROM FactOnlineSales fs
       INNER JOIN DimCustomer c
         ON c.CustomerKey = fs.CustomerKey
 GROUP BY fs.CustomerKey,
          c.MonthlyIncome

大概CustomerKey是唯一的，因此按不太唯一的列分组不会改变SUM总数。

Answer 2

您没有提及您使用的 SQL Server版本- 但如果您使用的是 SQL Server 2005或更高版本，则可以使用以下OVER()子句：

SELECT 
    fs.CustomerKey, 
    c.MonthlyIncome,
    TotalBought = SUM(fs.TotalCost) OVER(PARTITION BY fs.CustomerKey)
FROM 
    FactOnlineSales fs
INNER JOIN 
    DimCustomer c on c.CustomerKey = fs.CustomerKey

这基本上给了你CustomerKey，MonthlyIncome然后TotalCost对每个求和，CustomerKey并在你的输出中显示适当的值。GROUP BY在这种情况下不需要做 a

Answer 3

您可能在连接的 ON 子句中有错误。
您使用CustomerKey而不是Customer ID从DimCustomer表中。对于分组：您必须按未聚合的每一列进行分组，因此您可以包括NAME（因此您可以拥有描述性客户）和 MonthlyIncome.

SELECT 
    c."Customer ID",
    c.NAME, 
    c.MonthlyIncome,
    SUM(fs.TotalCost) as TotalBought
FROM 
    FactOnlineSales fs INNER JOIN DimCustomer c 
    on c."Customer ID" = fs.CustomerKey
GROUP BY 
    c."Customer ID",
    c.NAME,
    c.MonthlyIncome