title: Insert rows in table2 when row deleted in table1
body: <p>How can I do the following in Yii:</p>
  
  <p>I have the following 4 tables:</p>
  
  <pre><code>**Course**
  -idCourse;
  -title;
  -description;
  
  **Participant**
  -idParticipant;
  -name;
  -...
  
  **Register**
  -id;
  -idCourse;
  -idParticipant;
  
  **Pool**
  -idPool
  -idCourse
  -idParticipant
  </code></pre>
  
  <p>I want to achieve this: When deleting a Course, I want to find all the participant which where registered for this Course (in Register table) and put them in the Pool table.</p>
  
  <p>How can I do this? Please help </p>