How can I eliminate the duplicate values in my answer - sql-server

Question

I work with the AventureWorks2014 database in Microsoft SQL Server. I need to create a view that will show the CustomerID, the full name and the TOTAL amount sold to client through the web.
My problem is that I can't seem to get the values corresponding to a single customer add up so that a single customer answers to a single line in my result. This is the code I have, any help would be appreciated. I basically need to show the total amount sold to clients on the web.
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
Thanks

Answer 1

Sounds like you need to use GROUP BY and SUM(), example:
SELECT column-names
FROM table-name
WHERE condition
GROUP BY column-names
ORDER BY column-names
Such as:
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
Would return:
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 filters result rows to remove duplicates. What I think you want is to aggregate rows. Perhaps this will do what you want:
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
Note that I removed distinct, added sum operator on the amount you want to total, and group by the customer id and name fields (SQL Server requires that you list in the GROUP BY all result columns which are not being aggregated).

Answer 3

You can use the following VIEW using a GROUP BY on the SELECT:
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
Note: You only need one CONCAT function to concat all string values.