title: Doctrine & ManyToOne Foreign key issue
body: <p>I'm trying to create a relation between a <code>Language</code> entity and a <code>User</code> entity, one language has many users, but a user has one language.
  So I created this relation as follow :</p>
  <p>In User.php:</p>
  <pre><code>/**
   * @ORM\ManyToOne(targetEntity=&quot;Language&quot;, inversedBy=&quot;users&quot;)
   * @ORM\JoinColumn(name=&quot;language_id&quot;, referencedColumnName=&quot;id&quot;)
   */
  private $language;
  </code></pre>
  <p>In Language.php</p>
  <pre><code>/**
   * @var ArrayCollection
   * @ORM\OneToMany(targetEntity=&quot;User&quot;, mappedBy=&quot;language&quot;)
   */
  private $users;
  
  public function __construct()
  {
      $this-&gt;users = new ArrayCollection();
  }
  </code></pre>
  <p>I've just followed the Doctrine mapping documentation to create these lines of code.</p>
  <p>I've created the schema with <code>doctrine:schema:create command line,</code> and when I try to validate it, it says :</p>
  <blockquote>
  <p>[ERROR] The database schema is not in sync with the current mapping
  file.</p>
  </blockquote>
  <p>So I tried a <code>doctrine:schema:update --dump-sql</code> to see what's the cause of the problem :</p>
  <pre><code>ALTER TABLE user CHANGE language_id language_id INT DEFAULT NULL;
  </code></pre>
  <p>What could be the problem because I am very confused?</p>