title: Oracle DBMS_ALERT in Oracle 12c
body: <p>I have a table (<code>my_tab</code>) that contains a STATUS column against a specific ID in this same table.</p>
  
  <p>I need a means of being alerted via a DBMS_ALERT process of when the STATUS column changes value.</p>
  
  <p>I was looking at using a trigger to kick off the ALERT, i.e.:</p>
  
  <pre><code>create or replace trigger my_tab_upd after update of status on my_tab for each row
  begin
     dbms_alert.signal('mystatusalert', 'changed from '||:old.status||' to '||:new.status||'.');
  end;
  /
  </code></pre>
  
  <p>With this, how do I now get alerted/notified that this STATUS change has occurred within a PL/SQL procedure to now go off and perform another operation based on this STATUS change?</p>
  
  <p>Further to the above, with my application setup, there will be multiple users. Based on this, how can I target the alert for specific users/sessions so that the correct user gets their alert only and not someone else's.</p>
  
  <p>I am looking at checking the alert from a web based application (Oracle APEX), so don't want to lock the front-end up so any recommendations on this would be good.</p>
  
  <p>An example would be great.</p>