SQL Distinct Sum - sql

Question

SELECT DISTINCT
E.FirstName + ' ' + E.LastName [Full Name],
P.ProductName,
OD.Quantity
FROM Employees E,
Products P,
[Order Details] OD,
Orders O
WHERE
E.EmployeeID = O.EmployeeID
AND O.OrderID = OD.OrderID
AND OD.ProductID = P.ProductID
In the Northwind gives back duplicate FullNames and ProductNames because of the Quantity which is changed (because of the date shipped each time).
I want to present only a Name to a specific ProductName with the Total Quantity and not divided.

Answer 1

You need to use GROUP BY with SUM:
SELECT
e.FirstName + ' ' + e.LastName AS [Full Name],
p.ProductName,
SUM(od.Quantity) AS [Quantity]
FROM Employees e
INNER JOIN Orders o
ON o.EmployeeID = e.EmployeeID
INNER JOIN [Order Details] od
ON od.OrderID = o.OrderID
INNER JOIN Products p
ON p.ProductID = od.ProductID
GROUP BY
e.FirstName + ' ' + e.LastName,
p.ProductName
Note, you need to stop using the old-style JOIN syntax.

Answer 2

I think,it was a good question for discussion.
Correct query always depend upon your actual requirement.
I think your table is too much normalise.In such situation most of them will also keep Employeeid in order_detail table.
At the same time,most of them keep sum value in Order table.
Like sum of quantity,sum of amount etc per orderid in order table.
you can also create view without aggregate function joining all the table.
IMHO,Using Group By clause on so many column and that too on varchar column is bad idea.
Try something like this,
;With CTE as
(
SELECT
E.FirstName + ' ' + E.LastName [Full Name],
O.OrderID,od.qty,P.ProductName
FROM Employees E
inner join Orders O on E.EmployeeID = O.EmployeeID
inner join [Order Details] OD on o.orderid=od.orderid
inner join [Products] P on p.ProductID=od.ProductID
)
,CTE1 as
(
select od.orderid, sum(qty) TotalQty
from CTE c
group by c.orderid
)
select c.[Full Name],c1.TotalQty, P.ProductName from cte c
inner join cte1 c1 on c.orderid=c1.orderid