title: Yii model->findAll(), how to add relational table columns?
body: <p>I have two models.  They are DisnotificationUpdate and DisNotification.
  DisnotificationUpdate relations are as below.</p>
  
  <pre><code>public function relations()
      {
          // NOTE: you may need to adjust the relation name and the related
          // class name for the relations automatically generated below.
          return array(
              'user' =&gt; array(self::BELONGS_TO, 'Login', 'userid'),
              'notifi' =&gt; array(self::BELONGS_TO, 'Disnotification', 'notifi_id'),
  
          );
      }
  </code></pre>
  
  <p>It's attributes are as following.</p>
  
  <pre><code>public function attributeLabels()
      {
          return array(
              'id' =&gt; 'ID',
              'notifi_id' =&gt; 'Notifi',
              'view' =&gt; 'View',
              'userid' =&gt; 'Userid',
          );
      }
  </code></pre>
  
  <p>Disnotification model has following attributes.</p>
  
  <pre><code>public function attributeLabels()
      {
          return array(
              'id' =&gt; 'ID',
              'notification' =&gt; 'Notification',
              'owner' =&gt; 'Owner',
              'workspace_id' =&gt; 'Workspace',
              'postID' =&gt; 'Post',
              'pDate' =&gt; 'P Date',
          );
      }
  </code></pre>
  
  <p>I want to select values from DisnotificationUpdate and order by  values using 'pDate' in DisNotification.
  I tried as following.</p>
  
  <pre><code> $dataProvider=DisnotificationUpdate::model()-&gt;findAll(array(
          'condition' =&gt; 'userid=:userid',
          'order' =&gt; 'notifi.pDate ASC',
          'limit'=&gt;10,
          'params' =&gt; array(':userid' =&gt; $myid)
      ));
  </code></pre>
  
  <p>But it is giving an error saying, "Unknown column 'notifi.pDate' in 'order clause'". What I am doing wrong? Thanks.</p>