Imports System.Data.OleDb

Public Class Form1

  Private Sub Button1_Click(ByVal sender As System.Object, _
          ByVal e As System.EventArgs) Handles btnExecute.Click
      ExecuteSQL()
  End Sub

  Private Sub ExecuteSQL()
     'Connectionstring festlegen mit Hilfe des
     'ConnectionStringBuilders
    Dim builder As OleDbConnectionStringBuilder = New _
        OleDbConnectionStringBuilder

    With builder
      .DataSource = "Nordwind.mdb"
      .Provider = "Microsoft.Jet.OLEDB.4.0"
    End With

     'ConnectionString zusammenstellen
    Dim CONNSTRING As String = builder.ConnectionString

     'Verbindung aufbauen
    Dim conn As New OleDbConnection(CONNSTRING)

    conn.Open()
     'Den Select-Command entgegennehmen und die Tabelle füllen
    Dim da As New OleDbDataAdapter(txtSQLString.Text, conn)
    Dim tbl As New DataTable

     '***   Using conn  ***
     '**********************
     'sorgt dafür, dass die Verbindung wieder geschlossen wird,
     'wenn der Using-Block wieder verlassen wird.
    Using conn

    Try
      da.Fill(tbl)
    Catch ex As OleDbException
      MessageBox.Show(ex.Message, "Fehler bei der "_
             "Befehlsausführung:", MessageBoxButtons.OK, _
             MessageBoxIcon.Exclamation)
    End Try

     'Datenbindung ohne BindungSource:
     'Die DataTable wird direkt an die DataSource gebunden
    DataGridView1.DataSource = tbl

    lblCount.Text = tbl.Rows.Count.ToString
    End Using

     '*** End Using  ***
     '*******************
     'Hier angekommen.
     'wird die Connection automatisch wieder geschlossen
  End Sub

   'DataRow auslesen
   'Das Ereignis wird ausgelöst bei Doppelklick in eine Zelle
  Private Sub DataGridView1_CellContentClick(ByVal sender As _
          System.Object, ByVal e As _
          System.Windows.Forms.DataGridViewCellEventArgs) _
          Handles DataGridView1.CellContentClick

     'Die DataTable
    Dim tbl As DataTable = DirectCast(DataGridView1.DataSource, _
        DataTable)

     'Die DataRow der DataTable per Rows(e.RowIndex) ermitteln
    Dim obj As Object = DataGridView1.Rows(e.RowIndex)
     'Die Ansicht der DataRow (DataRowView)
    Dim rowView As DataRowView = _
        TryCast(DataGridView1.Rows(e.RowIndex).DataBoundItem, _
        DataRowView)

    If rowView Is Nothing Then
       Return
    End If

     'Die eigentliche DataRow
    Dim row As DataRow = rowView.Row

     'StringBuilder instanzieren
    Dim sb As New System.Text.StringBuilder

     'Durch die einzelnen Spalten der Tabelle iterieren
     'und mittels StringBuilder festhalten
    For Each spalte As DataColumn In row.Table.Columns
       'Spaltennamen
      sb.Append(spalte.ColumnName)
       'Spaltentyp
      sb.Append(" (" & spalte.DataType.ToString & "): ")
       'Inhalt des Datenfeldes
      sb.Append(row(spalte.ColumnName).ToString)
       'Zeilenumbruch
      sb.Append(vbNewLine)
    Next

     'Datenzeile ausgeben
    MessageBox.Show(sb.ToString, "Datenzeile:", _
               MessageBoxButtons.OK, MessageBoxIcon.Information)
  End Sub

  Private Sub Form1_Load(ByVal sender As System.Object, _
          ByVal e As System.EventArgs) Handles MyBase.Load

     'Ein paar Beispiele für SQL-SELECT-Statements
    With cboSelect
      .Items.Add("SELECT * FROM Bestellungen")
      .Items.Add("SELECT * FROM Kunden")
      .Items.Add("SELECT Firma, BestellNr, "_
       "Bestelldatum FROM Kunden, Bestellungen WHERE "_
       "Kontaktperson = 'Thomas Hardy'")
      .Items.Add("SELECT BestellNr, Bestelldatum FROM Kunden, "_
       "Bestellungen WHERE Firma = 'Frankenversand'")
      .Items.Add("SELECT Firma, BestellNr, Bestelldatum FROM "_
       "Kunden, Bestellungen WHERE Land = 'Deutschland'")
      .Items.Add("SELECT Firma, Telefon, Strasse, Plz, Ort FROM "_
       "Kunden WHERE Land = 'Deutschland' AND PLZ LIKE '5%'")
      .Items.Add("SELECT * FROM Kunden WHERE Ort = 'Madrid'")
      .Items.Add("SELECT * FROM Kunden WHERE Ort LIKE 'M%'")
      .Items.Add("SELECT Land, Plz, Ort, Strasse FROM Kunden "_
       WHERE Strasse LIKE '%place%'")
      .Items.Add("SELECT * FROM Kunden WHERE Ort LIKE 'M%' AND "_
       "Kontaktperson LIKE 'Hanna%'")
      .Items.Add("SELECT * FROM Kunden ORDER BY Ort")
      .Items.Add("SELECT * FROM Kunden WHERE KundenID = 'GODOS'")
      .Items.Add("SELECT KundenID, Ort, Telefon, TeleFax FROM "_
       "Kunden WHERE Kontaktperson = 'Sven Ottlieb'")
      .Items.Add("SELECT Firma, Kontaktperson, FirmaPosition "_
       "FROM Kunden WHERE Land = 'Deutschland'")
      .Items.Add("SELECT Firma, BestellNr, Bestelldatum FROM "_
       "Kunden, Bestellungen WHERE Land = 'Deutschland' AND "_
       "Lieferdatum > #05/01/1996#")
      .Items.Add("SELECT Land, Firma, BestellNr, Bestelldatum "_
       "FROM Kunden, Bestellungen WHERE Land = 'Deutschland' AND "_
       "Lieferdatum  > #006/01/1996#")
      .Items.Add("SELECT BestellNr, Bestelldatum, Firma FROM "_
       "Kunden, Bestellungen WHERE Firma = 'Frankenversand' AND "_
       "Bestelldatum > #01/01/1996#")
      .Items.Add("SELECT BestellNr, KundenID, Bestelldatum FROM "_
       "Bestellungen WHERE Bestelldatum > #08/11/1995#")
      .Items.Add("SELECT BestellNr, KundenID, Bestelldatum FROM "_
       "Bestellungen WHERE Bestelldatum < #08/11/1995#")
      .Items.Add("SELECT BestellNr, KundenID, Bestelldatum FROM "_
       "Bestellungen WHERE Bestelldatum BETWEEN #08/11/1995# "_
       "AND #01/01/1996#")
      .Items.Add("SELECT BestellNr, Bestelldatum FROM Kunden, "_
       "Bestellungen WHERE Kontaktperson = 'Henriette Pfalzheim'")
      .Items.Add("SELECT BestellNr, KundenID, Bestelldatum FROM "_
       "Bestellungen WHERE Bestelldatum BETWEEN #08/11/1995# AND "_
       "#01/01/1996#")
      .Items.Add("SELECT BestellNr, KundenID, Bestelldatum FROM "_
       "Bestellungen WHERE Bestelldatum BETWEEN #08/11/1995# AND "_
       "#01/01/1996#")
     End With

     cboSelect.SelectedIndex = 0
  End Sub

  Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As _
          System.Object, ByVal e As System.EventArgs) Handles _
          cboSelect.SelectedIndexChanged

    txtSQLString.Text = cboSelect.SelectedItem.ToString
    ExecuteSQL()
  End Sub

  Private Sub btnExit_Click(ByVal sender As System.Object, _
          ByVal e As System.EventArgs) Handles btnExit.Click
    Me.Close()
  End Sub
End Class