title: Change Notification with Oracle Dependency in C#
body: <p>I'm trying to get oracle database change notification in c#. I found 
  <a href="http://docs.oracle.com/cd/B19306_01/win.102/b14307/featChange.htm#BABDGFBH" rel="nofollow">this tutorial</a> about how to get these notifications. I've also created simple win form application for catching notifications</p>
  
  <pre><code>public partial class Form1 : Form
  {
      public Form1()
      {
          InitializeComponent();
          SetUpNotification();
      }
  
      private void SetUpNotification()
      {
          var login = "DATA SOURCE=XE;PERSIST SECURITY INFO=True;USER ID=USR;PASSWORD=PWD";
  
          OracleConnection conn = null;
          OracleDependency dep = null;
  
          try
          {
              conn = new OracleConnection(login);
  
              var cmd = new OracleCommand("select * from customer_details", conn);
  
              conn.Open();
  
              cmd.AddRowid = true;
              dep = new OracleDependency(cmd);
              cmd.Notification.IsNotifiedOnce = false;
  
              dep.OnChange += new OnChangeEventHandler(dep_OnChange);
          }
          catch(Exception e)
          {
              MessageBox.Show(e.Message, e.Source, MessageBoxButtons.OK, MessageBoxIcon.Error);
          }
      }
  
      void dep_OnChange(object sender, OracleNotificationEventArgs eventArgs)
      {
          MessageBox.Show(eventArgs.Details.ToString(), "Database changed");
      }
  }
  </code></pre>
  
  <p>Login string and OracleCommand cmd are 100% fine. I tried also to change database programmatically, it changed data in database, but didn't fired OnChange event. </p>
  
  <p>I also granted notifications tu USR user</p>
  
  <pre><code>grant change notification to USR
  </code></pre>
  
  <p>and job_queue_processes are greater than zero.</p>
  
  <p>Can be a problem in a fact, that I am using <strong>Express edition</strong> of oracle database?</p>