如何消除答案中的重复值

Question

我在 Microsoft SQL Server 中使用 AventureWorks2014 数据库。我需要创建一个视图来显示CustomerID、全名和通过网络销售给客户的总金额。

我的问题是，我似乎无法将与单个客户对应的值加起来，以便单个客户回答我的结果中的单行。这是我的代码，任何帮助将不胜感激。我基本上需要显示在网络上销售给客户的总金额。

if object_id('vTotalWebSalesPerCustomer', 'v') is not null
    drop view vTotalWebSalesPerCustomer;
go

create view vTotalWebSalesPerCustomer
as
    select distinct 
        c.CustomerID,
        ltrim(rtrim(concat(concat(concat(concat(concat(concat(concat(p.Title, ' '), p.LastName), ', '), ' '), p.FirstName), ' '), p.Suffix))) as NomClient,
        soh.TotalDue
    from
        [Sales].[Customer] as c
    left join 
        [Person].[Person] as p on c.CustomerID = p.BusinessEntityID
    left join 
        [Sales].[SalesOrderHeader] as soh on soh.CustomerID = c.CustomerID
    where 
        year(soh.OrderDate) = 2014 
        and datepart(quarter, soh.OrderDate) = 1 
        and [OnlineOrderFlag] = 1
go

select * 
from vTotalWebSalesPerCustomer

谢谢

Answer 1

听起来你需要使用 GROUP BY 和 SUM()，例如：

SELECT column-names
 FROM table-name
WHERE condition
GROUP BY column-names
ORDER BY column-names

如：

SELECT SUM(O.TotalPrice), C.FirstName, C.LastName
  FROM [Order] O JOIN Customer C 
    ON O.CustomerId = C.Id
 GROUP BY C.FirstName, C.LastName
 ORDER BY SUM(O.TotalPrice) DESC

会返回：

Sum         FirstName   LastName
117483.39   Horst       Kloss
115673.39   Jose        Pavarotti
113236.68   Roland      Mendel
57317.39    Patricia    McKenna
52245.90    Paula       Wilson
34101.15    Mario       Pontes
32555.55    Maria       Larsson

Answer 2

DISTINCT 过滤结果行以删除重复项。我认为你想要的是聚合行。也许这会做你想要的：

create view vTotalWebSalesPerCustomer as
    select      c.CustomerID,
                        ltrim(rtrim(concat(concat(concat(concat(concat(concat(concat(p.Title, ' '), p.LastName), ', '), ' '), p.FirstName), ' '), p.Suffix))) as NomClient,
                        sum(soh.TotalDue) as TotalDue
    from [Sales].[Customer] as c
    left join [Person].[Person] as p on c.CustomerID = p.BusinessEntityID
    left join [Sales].[SalesOrderHeader] as soh on soh.CustomerID = c.CustomerID
    where year(soh.OrderDate) = 2014 and datepart(quarter, soh.OrderDate)=1 and [OnlineOrderFlag] = 1
    group by c.CustomerID,NomClient

请注意，我删除了 distinct，在您想要总计的金额上添加了 sum 运算符，并按客户 ID 和名称字段分组（SQL Server 要求您在 GROUP BY 中列出所有不属于的结果列汇总）。

Answer 3

您可以在SELECT 上使用GROUP BY 来使用以下VIEW：

IF OBJECT_ID('vTotalWebSalesPerCustomer', 'v') IS NOT NULL
    DROP VIEW vTotalWebSalesPerCustomer;
GO

CREATE VIEW vTotalWebSalesPerCustomer AS
    SELECT 
        x.CustomerID,
        LTRIM(RTRIM(CONCAT(p.Title, ' ', p.LastName, ', ', p.FirstName, ' ', p.Suffix))) AS NomClient,
        x.TotalDue
    FROM (
        SELECT 
            c.CustomerID AS CustomerID,
            SUM(soh.TotalDue) AS TotalDue
        FROM [Sales].[Customer] AS c
        LEFT JOIN [Sales].[SalesOrderHeader] AS soh ON soh.CustomerID = c.CustomerID
        WHERE YEAR(soh.OrderDate) = 2014 AND DATEPART(quarter, soh.OrderDate) = 1 AND [OnlineOrderFlag] = 1
        GROUP BY c.CustomerID
    )x LEFT JOIN [Person].[Person] AS p ON x.CustomerID = p.BusinessEntityID
GO

注意：您只需要一个CONCAT 函数即可连接所有字符串值。