title: RAISE_APPLICATION_ERROR issue
body: <p>I have developed a trigger that checks the validity of a date. It works fine because it prevents me from storing an invalid date, but I also get a weird error message and I can't figure out why. My code is the following:</p>
  
  <pre><code>CREATE OR REPLACE TRIGGER  "CHECKDATEVALIDITY" 
  BEFORE INSERT OR UPDATE
  ON Event
  FOR EACH ROW
  BEGIN
  IF :NEW.day &lt; 1 OR :NEW.month &lt; 1 OR :NEW.month &gt; 12
      THEN
              RAISE_APPLICATION_ERROR(-20101, 'Wrong date');
  END IF;
  
  IF :NEW.month = 4 OR :NEW.month = 6 OR :NEW.month = 9 OR :NEW.month = 11 
      THEN
          IF :NEW.day &gt; 30
              THEN
                  RAISE_APPLICATION_ERROR(-20101, 'Wrong date');
          END IF;
  ELSIF :NEW.month = 2
      THEN
          IF (mod(:NEW.year, 4) = 0)
              THEN
                  IF :NEW.day &gt; 29
                      THEN
                          RAISE_APPLICATION_ERROR(-20101, 'Wrong date');
                  END IF;
          ELSIF :NEW.day &gt; 28
              THEN
                  RAISE_APPLICATION_ERROR(-20101, 'Wrong date');
          END IF;
  ELSE
      IF :NEW.day &gt; 31
          THEN
              RAISE_APPLICATION_ERROR(-20101, 'Wrong date');
      END IF;
  
  END IF;
  
  END checkDateValidity;
  </code></pre>
  
  <p>The error I get is:</p>
  
  <blockquote>
    <p>error ORA-20101: Wrong date ORA-06512: on "USER587.CHECKDATEVALIDITY", line 28 ORA-04088: error while executing trigger 'USER578.CHECKDATEVALIDITY'.</p>
  </blockquote>
  
  <p>Also I have noticed that I get the error from the line next to the RAISE_APPLICATION_ERROR invoked. What does issue the error?</p>