Question

I have an order table like this

ID   OrderNumber        Item           Quantity        Subtotal     OrderedBy

1    2012-0001-12       Barbie            1              10         Thomas
2    2012-0001-12       Ken               2              20         Thomas
3    2012-0001-23       Mickie            4              28         Thomas
4    2012-0001-23       Minnie            3              21         Thomas
5    2012-0002-12       Barbie            1              10         Peter
6    2012-0003-01       Cake              1              12         Thomas
7    2012-0003-02       Wine              1              70         Thomas

In the OrderNumber the first two parts, that is for the first row 2012-001, is the actual order id.
The last part appended is the SupplierID which is not relevant in this case.

So this table now has three Orders

OrderNumber        OrderCount          Total        OrderedBy

2012-0001              4                 79          Thomas
2012-0002              1                 10          Peter
2012-0003              2                 82          Thomas

Currently I am looping through the DataTable after SELECTing everything from database and adding it to another generic list when 2012-0001 changes to 2012-0002. Meanwhile I am also adding the itemCount and total in the loop.

Is there a way to get the orders in a table(sql) or as an enumerable collection(linq) without this much hassle?

Answer 1

If you are just looking to create your second table, then you could try the following:

SELECT SUBSTRING(OrderNumber, 1, 9) AS OrderNumber
    , COUNT(*) AS OrderCount
    , SUM(Subtotal) AS Total
    , OrderedBy
FROM [Table]
GROUP BY SUBSTRING(OrderNumber, 1, 9), OrderedBy

This makes the assumption that a single order will always be done by the same person.