PHP Fatal error: Call to a member function query() on null : <p>I am new in php, and wonder why I getting this, need expert to guide.  Thanks.</p>

<p>PHP Fatal error:  Call to a member function rowCount() on resource in C:\inetpub\wwwroot\xxx\xxx.php on line 9</p>

<pre><code>&lt;?php
include 'connect_db.php';
$conn = null;

$sqlGetFeedback = "Select * from t_abc";

$resFB = $conn-&gt;query($sqlGetFeedback);
$rows = array();

if($resFB-&gt;rowCount()){
    echo json_encode($resFB-&gt;fetchAll(PDO::FETCH_ASSOC));
} else {    
    echo '[{}]';
}
?&gt;
</code></pre>
