title: IS NOT NULL not working in Yii Active Record
body: <p>I am trying something like this:</p>
  
  <pre><code>public function search() {
  
          $criteria = new CDbCriteria;
  
          $criteria-&gt;compare('user_details_id', $this-&gt;user_details_id);
          $criteria-&gt;compare('user_type_id', $this-&gt;user_type_id);
          $criteria-&gt;compare('customer_basics_id', $this-&gt;customer_basics_id);
          $criteria-&gt;compare('user_address_id', $this-&gt;user_address_id);
          $criteria-&gt;compare('user_city_id', $this-&gt;user_city_id);
          $criteria-&gt;compare('is_active', $this-&gt;is_active);
          $criteria-&gt;compare('create_dttm', $this-&gt;create_dttm, true);
          $criteria-&gt;compare('update_dttm', $this-&gt;update_dttm, true);
  
          // if condition is working
          if (isset($_GET['ulip'])) {
              $criteria-&gt;addCondition(
                      "customer_basics_id=" . CustomerBasics::getCustomerBasicsId(Yii::app()-&gt;session['user_id']), "AND"
              );
              $criteria-&gt;addCondition("user_city_id IS NULL");
          // else condition is working
          } else {
              $criteria-&gt;addCondition(
                      "customer_basics_id=" . CustomerBasics::getCustomerBasicsId(Yii::app()-&gt;session['user_id']), "AND"
              );
              $criteria-&gt;addCondition("user_city_id IS NOT NULL");
          }
  
  
      return new CActiveDataProvider($this, array(
          'criteria' =&gt; $criteria,
          'pagination' =&gt; array(
              'pageSize' =&gt; 10,
          ),
      ));
  }
  </code></pre>
  
  <p>Here the issue is <code>if</code> condition is working fine and showing results according to the condition but else part is not working and it returns nothing. I think <code>IS NOT NULL</code> is not working here. </p>
  
  <p>What is the issue ?</p>