title: Oracle MERGE does not INSERT
body: <p>I have this simple example I can't seems to get working : </p>
  
  <pre><code>MERGE INTO mytable  mt
  USING dual
  ON (mt.id = 'AAA' )  
  WHEN MATCHED THEN 
      UPDATE SET mt.name = 'updated'
  WHEN NOT MATCHED THEN 
      INSERT (mt.id , mt.name )
      VALUES ('AAA', 'Gooood' );
  </code></pre>
  
  <p>If a 'AAA' record exists in the table, it is updated successfully. </p>
  
  <p>But if does not exists, it is not inserted : </p>
  
  <pre><code>Affected rows: 0
  Time: 0.003ms
  </code></pre>
  
  <p>Any clue on what I am doing wrong ?</p>