title: insert if not exists Codeigniter
body: <p>my controller:</p>
  
  <pre><code>function getFeed()
  {
     $feed_url = $this-&gt;input-&gt;get("url");
     $content = file_get_contents($feed_url);
     $x = new SimpleXmlElement($content);
  
      foreach($x-&gt;channel-&gt;item as $entry) {
          $feeds[] = array(
                           'title' =&gt; (string)$entry-&gt;title,
                           'url'=&gt; (string)$entry-&gt;link,
                           'username' =&gt; $this-&gt;session-&gt;userdata('username')                      
                  );
  
          $this-&gt;load-&gt;model('membership_model');
          $this-&gt;membership_model-&gt;feeds($feeds);
      }
  </code></pre>
  
  <p>Model:</p>
  
  <pre><code>function feeds($feeds_data)
  {   
          $this-&gt;db-&gt;insert_batch('feeds', $feeds_data);
  }
  </code></pre>
  
  <p>Is there a function to insert if only the row doesn't exists in the table? I have a table with 4 column : id,title,url,username. I have an anchor when i click him it calls geFeed function and insert the info into table. But i want to insert only if not exists.</p>