C#

pulbic  class A
{
  public void func1()
  {
  }
   ....
}

public class B : A
{
   ...
}

string Constr = @"Provider=Microsoft.Jet.OLEDB.4.0; Data Source= " + Application.StartupPath + @"/" +
                   textBoxAccessFile.Text + ";Jet OLEDB:Database Password= " + textBoxAccessPassword.Text;
               OleDbConnection Conn = new OleDbConnection(Constr);
               try
               {
                   Conn.Open();
                   DataTable dt = Conn.GetSchema("tables");
                   Conn.Close();
                   for (int i = 0; i < dt.Rows.Count; i++)
                   {
                       listViewDbTables.Items.Add(dt.Rows[i].ToString());
                   }
               }
               catch (Exception ex)
               {
                   MessageBox.Show("Error: " + ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
               }

BackgroundMusic = new MCIPlayback(Properties.Settings.Default.SOUNG_MUTE);

BackgroundMusic.Open(soundFilePath, "mpegvideo");//mp3player

BackgroundMusic.Play();

    private String alias;
  
    /// <summary>
    /// Initializes a new instance of the <see cref="MCIPlayback"/> class.
    /// </summary>
    public MCIPlayback(bool m)
    {
      muted = m;
      this.alias = Guid.NewGuid().ToString("N");
    }

    /// <summary>
    /// Öffnet einen Stream.
    /// </summary>
    /// <param name="file">Datei</param>
    /// <param name="type">Medientyp (siehe Klasssenbeschreibung)</param>
    public void Open(string file, string type)
    {
      this.alias = Guid.NewGuid().ToString("N");
      name = file;
       string cmd = "open \"" + name + "\" type " + type + " alias \"" + alias + "\"";
       // Guid.NewGuid().ToString("N") 
        
      int errCode = mciSendString(cmd, null, 0, IntPtr.Zero);
      if (errCode == 0)
        isOpen = true;
      CheckError(errCode);
    }


    /// <summary>
    /// Plays the new track. :-)
    /// </summary>
    /// <param name="file">The file.</param>
    public void PlayNewTrack(string file)
    {
      Stop();
      //Close();
      Open(file, "mpegvideo"); //mpegvideo
      Play();
    }


    /// <summary>
    /// Mutes this instance.
    /// </summary>
    public void mute()
    {
      muted = true;
      Pause();
    }



    /// <summary>
    /// Spielt geladenen Stream ab.
    /// </summary>
    public void Play()
    {
      if (muted)
      {
        Pause();
        return;
      }
      if (!isOpen)
        return;
     // SeekToStart();
      string cmd = "play \"" + name + "\"";
      int errCode = mciSendString(cmd, null, 0, IntPtr.Zero);
      CheckError(errCode);
    }
}