Vlori Datatable

dim DT as DataTable
dim text_1 as string   ' stringa per contenere il file txt

...
...  recupero i dati tramite sql
...
Quindi 
            For Each MyRow As DataRow  in dt.Rows
                For Each MyCol As DataColumn In dt.Columns
                        text_1 = text_1  & MyCol.ToString & ";"
                next
                text_1 = text_1 & vbCrLf
            next

 Dim d As New DataTable

        d.Columns.Add("uno")
        d.Columns.Add("due")
        d.Columns.Add("tre")

        Dim dr As DataRow = d.NewRow()

        dr("uno") = 1
        dr("due") = 2
        dr("tre") = 3

        d.Rows.Add(dr)


        For Each r As DataRow In d.Rows

            Dim i As Integer = 0

            While i <= d.Columns.Count

                MessageBox.Show(r(i))
                i = i + 1

            End While


        Next