VB.NET LINQ群组由多列组成 [英] VB.NET LINQ Group By Multiple Columns

问题描述

我有以下LINQ代码，它有一个语法错误，我不知道如何解决它

I have the following LINQ code which has a syntax error and i've no idea how to fix it

         Dim query =
        From row In mainDatatable.AsEnumerable

    'the syntax Error is in the following line
      Group row By new  { row.Field(Of Double)("cprice") , row.Field(Of Integer)("ccategory")} 
Into ProductGroups
    '**************************

                Dim grpNumber = 1
                For Each grp In query
                    For Each row In grp.ProductGroups
                        row.SetField("gnum", grpNumber)
                    Next
                    grpNumber += 1
                Next


            End Sub

所以我做错了什么？

以下是表格的样子，我想按cprice和ccategory列分组

Here is how the table looks like and i want to group by the columns cprice and ccategory

+---------------+---------------+-----------+------+
| Product Name  | cprice        | ccategory | gnum |
+---------------+---------------+-----------+------+
| Skirt Red     |            99 |         1 |      |
| Jeans Blue    |            49 |         2 |      |
| Jeans Black   |            49 |         2 |      |
| Skirt Blue    |            99 |         1 |      |
| T-shirt White |            20 |         2 |      |
| T-shirt Green |            20 |         2 |      |
| Jeans Grey    |            49 |         2 |      |
+---------------+---------------+-----------+------+

推荐答案

试试这个：

new with { Key.Price = row.Field(Of Double)("cprice") ,
           Key.Category = row.Field(Of Integer)("ccategory")

使用键修饰符，这会创建一个匿名类型，它基于成员的平等实现相等性。

Uisng the Key modifier, this creates an anonymous type that implements equality based on equality of its members.

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