Question

In a VB.NET how can I loop through an an Access database without loading it to a DataGridView or loading it to a DataGridView and unload it after a comparison function finshed its work?

Answer 1

Using DataReader you can loop thru data, one row at a time without necessity of loading entire result set into DataTable/GridView.

Example usage (from http://msdn.microsoft.com/en-us/library/system.data.oledb.oledbdatareader(v=vs.90).aspx)

Public Sub ReadData(ByVal connectionString As String, _
    ByVal queryString As String)
    Using connection As New OleDbConnection(connectionString)
        Dim command As New OleDbCommand(queryString, connection)

        connection.Open()

        Dim reader As OleDbDataReader = command.ExecuteReader()
        While reader.Read()
            Console.WriteLine(reader(0).ToString())
        End While
        reader.Close()
    End Using 
End Sub

You pass connection string to your MS Access Database, and SELECT query to run. Example outputs data from the 1st column to console – but you can replace it with your own logic