title: I get an error in PostgreSql: number of referencing and referenced columns for foreign key disagree
body: <p>I'm creating a table, but I get this error:</p>
  <blockquote>
  <ul>
  <li>number of referencing and referenced columns for foreign key disagree.</li>
  </ul>
  </blockquote>
  <p>I don't know how to solve it. I think that it may be a problem with declaring 3 foreign keys, but, I'm not sure about it.</p>
  <p>What is the problem?</p>
  <pre class="lang-sql prettyprint-override"><code>Create table Trasllat
  (
  Data Date,
  Codi_Empleat Integer,
  Nom_agencia Varchar(30),
  Data_fi Date,
  Primary key (Data, Codi_Empleat),
  Foreign key (Data) references Data on delete cascade,
  Foreign key (Codi_empleat) references Empleat on delete cascade
  Foreign key (Nom_agencia) references Agencia on delete cascade
  );
  </code></pre>