title: How to avoid multiplication when click on combobox
body: <p>Hello when you click on a field of the combobox and automatic all values are doubled. Once they clicked once again they are tripled again.
  How can I fix that ?</p>
  
  <p>My code:</p>
  
  <pre><code>connection.Open();
  
  MySqlCommand command = new MySqlCommand(service.selectOnlyWorkerName(), connection);
  MySqlDataAdapter da = new MySqlDataAdapter(command);
  
  using (DataTable dt = new DataTable())
  {
      da.Fill(dt);
      foreach (DataRow dr in dt.Rows)
      {
          comboBox1.Items.Add(dr["worker_name"]);
      }
  }
  
  connection.Close();
  </code></pre>