title: php mysqli prepared statements stored procedures OUT parameter
body: <p>I've got a question that involves the use of stored procedures in mysqli prepared statements.
  The code snippet I'll show does work, I'd just like to know why.
  The prepared statement calls a stored procedure which takes 6 parameters, where the 6th is an OUT parameter.</p>
  
  <pre><code>    if (!($stmt = $this-&gt;sql-&gt;prepare("CALL registerUser(?,?,?,?,?,?);"))) { ... }
      $stmt-&gt;bind_param("issisi", $id, $email, $pwd, $ip, $actKey, $notUsed);
      $stmt-&gt;execute();
      $stmt-&gt;bind_result($isSuccessful);
      $stmt-&gt;fetch();
      $stmt-&gt;close();
      $this-&gt;sql-&gt;close();
  </code></pre>
  
  <p>The OUT parameter is binded to</p>
  
  <pre><code>$notUsed
  </code></pre>
  
  <p>Which does not yield any value after executing, but</p>
  
  <pre><code>$isSuccessful
  </code></pre>
  
  <p>which I binded to the result, does return the OUT parameter from the procedure, this return value can be 0 or 1, and I've confirmed it several times.
  I just don't understand why this is happening, because the procedure doesn't produce any results.</p>