title: In ZF2 how to execute OR condition in WHERE clause
body: <p>In my model:</p>
  
  <pre><code>$rowset = $this-&gt;tableGateway-&gt;select(array('username' =&gt; $identifier));
  $row = $rowset-&gt;current();
  return $row;
  </code></pre>
  
  <p>It executes the following query:</p>
  
  <pre><code>SELECT * FROM member WHERE username='&lt;&lt; ENTERED VALUE &gt;&gt;'; 
  </code></pre>
  
  <p>but I want execute the following query:</p>
  
  <pre><code>SELECT * FROM member WHERE username='&lt;&lt; ENTERED VALUE &gt;&gt;' OR id_customer='&lt;&lt; ENTERED VALUE &gt;&gt;'; 
  </code></pre>
  
  <p>What are the changes I have to make in model file?</p>
  
  <p>And please suggest useful blog regarding this. I cant find answer for this in ZF2 Documentation.</p>