保存前取消设置属性。

 $model->unsetAttributes(array("id_entry"));
public function actionUpdate($id)
{ 
    $model=$this->loadModel($id);
    // Uncomment the following line if AJAX validation is needed
    // $this->performAjaxValidation($model);
    if(isset($_POST['Entrydata']))
    {
        $_POST['Entrydata']['photo'] = $model->photo;
        $model->attributes=$_POST['Entrydata'];
        $uploadedFile = CUploadedFile::getInstance($model,'photo');
         // Unset Primary Key value.
         $model->unsetAttributes(array("id_entry"));
        if($model->save())
        {
            if(!empty($uploadedFile))  // check if uploaded file is set or not
            {
             $uploadedFile->saveAs(Yii::app()->basePath.'/../images/'.$model->photo); // image will uplode to rootDirectory/banner/
            }  
            $this->redirect(array('view','id'=>$model->id_entry)); 
        }

    }
    $this->render('create',array(
        'model'=>$model,
    ));
}