SQL adding only two columns with the same data
<p>I need to add an administrator and a date into an column but I can only have two administrators per year, how do I do that?
I have this:</p>

<pre><code>PROCEDURE regista_administrador (
    proprietario_in         IN administra.proprietario%TYPE,
    ano_in          IN administra.ano%TYPE)
  IS
  BEGIN
    SELECT ano INTO ano_in FROM administra WHERE (ano = ano_in);

    IF (SQL%ROWCOUNT = 0) THEN
      RAISE_APPLICATION_ERROR(-20003,   -- Código definido pelo programador.
                              'Já existem dois administradores nesse ano.');
    ELSE
      INSERT INTO administra(proprietario, ano)
           VALUES (proprietario_in, ano_in);
    END IF;
   EXCEPTION
    WHEN OTHERS THEN RAISE;
  END regista_administrador;
</code></pre>