title: MySQL Reflexive/recursive relation
body: <p>I am having a problem trying to create the following table:</p>
  
  <pre><code>CREATE TABLE autor 
  (
  id_autor VARCHAR (2),
  nom_autor VARCHAR (30),
  rfc_autor VARCHAR (15),
  pseudo_id VARCHAR (2), 
  PRIMARY KEY (id_autor),
  FOREIGN KEY (pseudo_id) REFERENCES autor(id_autor)
  );
  </code></pre>
  
  <p>When I try to run the following script:</p>
  
  <pre><code>INSERT INTO `revistas`.`autor` (`id_autor`, `nom_autor`, `rfc_autor`,`pseudo_id`) VALUES ('A3', 'Quijote','','A7');
  </code></pre>
  
  <p>MySQL shows: </p>
  
  <pre><code>Error Code: 1452. Cannot add or update a child row: a foreign key constraint fails (`revistas`.`autor`, CONSTRAINT `autor_ibfk_1` FOREIGN KEY (`pseudo_id`) REFERENCES `autor` (`id_autor`))
  </code></pre>
  
  <p>Any idea why?</p>
  
  <p>Thanks a lot!</p>