vb.net - 当其他 2 个列值相同时，LINQ 对某些列求和

Question

我有下表

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

使用 LINQ 我想对具有相同名称 catid 的行求和并将其保存到相同的数据表中

所以结果就是这张表

+-------+--------+----------+
| 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();

编辑:刚刚注意到它带有 VB 标记。对不起。嗯，应该是这样的:

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)
}