SQL Server - GROUP BY on one column

Question

I\'m trying to get orders from an orderview. In my view I do have some rows with exactly the same values, but I want to group these values on orderid and take the sum of the

Answer 1

Assuming the other columns are functionally dependent on the grouping column, the simplest answers are either

a. Group by the other columns as well:

SELECT Order_id, Customer_id, Article_id, Delivery_date, sum(Quantity)
FROM Orders
GROUP BY Order_id, Customer_id, Article_id, Delivery_date

or

b. Use an aggregate function such as max:

SELECT Order_id, max(Customer_id), max(Article_id), max(Delivery_date), sum(Quantity)
FROM Orders
GROUP BY Order_id

My personal preference is the second approach, as I think it is clearer than the first in indicating which items are actually required for grouping, as opposed to which are merely being grouped to get round the ungrouped/unaggregated column problem.