title: ISNULL(value, 0) in WHERE clause MYSQL
body: <p>I have this requets:</p>
  
  <pre><code>SELECT sc.no, scl.quantite, scl.description, scl.poids, scl.prix, sl_ref.refsl, sl_ref.codetva, sl_ref.tauxtva, sl_ref.compte 
  FROM shop_commande 
  AS sc, shop_commande_ligne AS scl, selectline_ref AS sl_ref 
  WHERE sc.id = scl.shop_commande_id 
  AND sl_ref.refshop = ISNULL(scl.shop_article_id, 0) 
  AND sc.id NOT IN (SELECT id_command FROM selectline_flag)
  </code></pre>
  
  <p>Sometimes, in <em>sl_shop_article_id</em>, there is a NULL value. What I want is to replace it by 0 so the clause:</p>
  
  <pre><code>sl_ref.refshop = scl.shop_article_id
  </code></pre>
  
  <p>can work even if <em>scl.shop_article_id</em> is NULL. To do that I tried to use the ISNULL function but it makes the request wrong and I get there error:</p>
  
  <p><em>1582 - Incorrect parameter count in the call to native function 'ISNULL'</em></p>
  
  <p>How can I use it ?</p>