Question

i’ve the following table

+-------+--------+----------+
| catid |  name  | quantity |
+-------+--------+----------+
|     1 | table  |       10 |
|     2 | chair  |        5 |
|     2 | chair  |       10 |
|     1 | table  |       10 |
|     2 | chair  |       15 |
|     3 | pencil |       20 |
+-------+--------+----------+

using LINQ i want to sum the quanitiy for the rows that have the same name catid and save this to the same datatable

so the result would be this table

+-------+--------+----------+
| catid |  name  | quantity |
+-------+--------+----------+
|     1 | table  |       20 |
|     2 | chair  |       30 |
|     3 | pencil |       20 |
+-------+--------+----------+

Answer 1

var result = (from row in YourTable
             group row by new {row.catid, row.name}
             into grp
                    select new
                    {
                        grp.Key.catid,
                        grp.Key.name,
                        Quantity = grp.Sum(row => row.Quantity)
                    }).ToList();

Edit: just noticed it’s VB tagged. Sorry for that. Well, should be something like this:

Dim result = From row In YourTable
    Group By Key = New With {row.catid, row.name} Into Group
Select New With 
{ 
.Catid = Key.catid, 
.Name =  Key.Name, 
.Quantity =  Group.Sum(Function(x) x.quantity)
}