vb linq使用left join分组并给出Sum从两个数据表中选择

' 创建示例数据表
Dim Table1 As New DataTable()
Table1.Columns.Add("ID", GetType(Integer))
Table1.Columns.Add("Value", GetType(Integer))
Table1.Rows.Add(1, 10)
Table1.Rows.Add(2, 20)
Table1.Rows.Add(3, 30)

Dim Table2 As New DataTable()
Table2.Columns.Add("ID", GetType(Integer))
Table2.Columns.Add("Value", GetType(Integer))
Table2.Rows.Add(1, 100)
Table2.Rows.Add(2, 200)
Table2.Rows.Add(4, 400)

' 使用LINQ进行左连接分组并选择Sum
Dim query = From t1 In Table1.AsEnumerable()
            Group Join t2 In Table2.AsEnumerable()
            On t1.Field(Of Integer)("ID") Equals t2.Field(Of Integer)("ID")
            Into Group
            From g In Group.DefaultIfEmpty()
            Group By t1ID = t1.Field(Of Integer)("ID"), t1Value = t1.Field(Of Integer)("Value")
            Into Sum(t1Value), Sum(t2Value) = Sum(If(g IsNot Nothing, g.Field(Of Integer)("Value"), 0))

' 遍历结果并输出
For Each result In query
    Console.WriteLine("ID: " & result.t1ID)
    Console.WriteLine("Sum of Table1.Value: " & result.t1Value)
    Console.WriteLine("Sum of Table2.Value: " & result.t2Value)
    Console.WriteLine()
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