Recently I needed GROUP BY feature applied to a DataSet in VB.NET. I found the following article Implement a DataSet GROUP BY Helper Class in Visual C# .NET on MSDN, which was very useful.

Nipun Tomar helped me converting C# code to VB.NET, which is attached in this article. This is what CreateGroupByTable method looks like. See the attached source code for more details.

Public Function CreateGroupByTable(ByVal TableName As String, ByVal SourceTable As DataTable, ByVal FieldList As String) As DataTable

  If FieldList Is Nothing Then
    Throw New ArgumentException("You must specify at least one field in the field list.")
  Else
    Dim dt As DataTable = New DataTable(TableName)
    ParseGroupByFieldList(FieldList)

    For Each Field As FieldInfo In GroupByFieldInfo
       Dim dc As DataColumn = SourceTable.Columns(Field.FieldName)
       If Field.Aggregate Is Nothing Then
         dt.Columns.Add(Field.FieldAlias, dc.DataType, dc.Expression)
       Else
         dt.Columns.Add(Field.FieldAlias, dc.DataType)
       End If
    Next

  If Not (ds Is Nothing) Then
     ds.Tables.Add(dt)
  End If

  Return dt
End If
End Function