title: auto inrement in the foregin key of a mysql database tabel doesen't work
body: <p>this is the error :</p>
  <p>Query error:</p>
  <blockquote>
  <p>#1833 - Cannot change column 'id_utente': used in a foreign key constraint 'effettua_ibfk_2' of table 'u205688162_royalartx.effettua'</p>
  </blockquote>
  <p>this is the table query :</p>
  <pre><code>CREATE TABLE utente
  (
    nome VARCHAR(256) NOT NULL,
    email VARCHAR(256) NOT NULL,
    password VARCHAR(256) NOT NULL,
    id_utente INT NOT NULL,
    PRIMARY KEY (id_utente)
  );
  </code></pre>
  <p>this is the query for adding auto increment for id_utente in utente table:</p>
  <pre><code>ALTER TABLE `utente` CHANGE `id_utente` `id_utente` INT(11) NOT NULL AUTO_INCREMENT;
  </code></pre>