>>>>Assume I have a datatable in a dataset with columns called ItemName and Quantity. Due to changes by the customer, there will now be multiple rows with the same ItemName and a Quantity of 1. The app used to have one row for the item and the total quantity.
>>>>
>>>>How do I combine the DT so that there is again one row with the total quantity?
>>>
>>>Do you want to save the totalled datatable to the backend? If so will this just be a one-off (tidy up) operation ?
>>>Or do you just need the totalled version to work with temporarily in the app ?
>>
>>Temporarily. It wont be sent to the DB.
>
>Something like:

var v = from x in dataTable.AsEnumerable()
>                    group x by x.Field<string>("ItemName") into g
>                    select new
>                    {
>                        ItemName = g.Key,
>                        Quantity = g.Sum(x => x.Field<int>("Quantity"))
>                    };
>
>//The above might be enough to work with?
>//If not then this would get it into a revised DataTable - but there's probably something better....
>
>            List<DataRow> al = new List<DataRow>();
>
>            foreach (var x in v)
>            {
>                DataRow dr = dataTable.NewRow();
>                dr["ItemName"] = x.ItemName;
>                dr["Quantity"] = x.Quantity;
>                al.Add(dr);
>            }
>            dataTable.Rows.Clear();
>            foreach (DataRow dr in al)
>            {
>                dataTable.Rows.Add(dr);
>            }

Hey Viv,

I implemented this code, and while is does merge the rows, the only columns with data in them are Part_Number (Sorry, it's not called ItemName ) and Quantity. I tried this:

private void CombineDuplicateRows()
{
    DataTable table = csCOSApp.ActiveProject.dsDataStore.Tables[0];

    var v = from x in table.AsEnumerable()
            group x by x.Field<string>("Part_Number") into g
            select new
            {
                Part_Number = g.Key,
                Quantity = g.Sum(x => x.Field<int>("Quantity")),
                RowId = x.RowId,
                ProjectId = x.ProjectId,
                ProductId = x.ProductId,
                Product_Series = x.Product_Series,
                Product_Number = x.Product_Number,
                Product_Name = x.Product_Name,
                Product_Description = x.Product_Description,
                PartId = x.PartId,
                Part_Description = x.Part_Description,
                New_Part_Number = x.New_Part_Number,
                Keyword = x.Keyword,
                Category = x.Category,
                TribalNumber = x.TribalNumber,
                WhseQty1 = x.WhseQty1,
                WhseQty2 = x.WhseQty2,
                PartPrice = x.PartPrice,
                PartRatio = x.PartRatio
            };

    List<DataRow> al = new List<DataRow>();

    foreach (var x in v)
    {
        DataRow dr = table.NewRow();
        dr["Part_Number"] = x.Part_Number;
        dr["Quantity"] = x.Quantity;
        al.Add(dr);
    }

    table.Rows.Clear();
    foreach (DataRow dr in al)
    {
        table.Rows.Add(dr);
    }
}

but it doesn't know what 'x' is in the anonymous type. My Linq is not too good here. Could use some help.