Dim cs As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=...."
        Dim conn As New OleDbConnection(cs)
        Dim cmd As New OleDbCommand("UPDATE table SET somefield=true Where" & _
          "id=1", conn)
        conn.Open()
        Dim res As Integer = cmd.ExecuteNonQuery()
        conn.Close()

UPDATE table SET somefield=? Where id=?

Those people who think they know everything are a great annoyance to those of us who do - Isaac Asimov