title: Stuck on a simple query - OUTER JOIN
body: <p>I have a simple query to get, but I'm stuck and I really can't figure out how to do this.
  More specifically:
  The table <code>Allarmi</code> has a lot of entries, which i show all grouped by <code>Allarmi.IDComponente</code></p>
  
  <p>something like this</p>
  
  <pre><code>SELECT * 
  FROM ALLARMI AS ALLARMI
  WHERE ID_CELLA = 1
  GROUP BY ID_Componente
  </code></pre>
  
  <p>I only need to add to this table a <code>COUNT</code> column, something like</p>
  
  <pre><code>(SELECT COUNT( * ) 
  FROM allarmi
  WHERE isAttivo = 1
  GROUP BY id_componente)
  </code></pre>
  
  <p>but I would like to show <code>COUNT</code> even when its <code>0</code> or <code>NULL</code></p>
  
  <p>How can I do it?
  Thanks in advance</p>