title: Create a trigger to restrict any user to access the table EMP for modification on weekends
body: <p>I have a table <code>emp</code> and fire a trigger which will prevent the access of some specific user on weekends. How do I obtain the current user?</p>
  
  <p>I am unable to complete the trigger body as follows:</p>
  
  <pre><code>BEGIN
  IF TO_CHAR(SYSDATE,'DAY')='SUNDAY' THEN....?
  </code></pre>