yii?CDbCriteria

选择 Date Form 和 Date To,点 Search按钮,会查询出这两个日期间的数据  public function search() {        $criteria = new CDbCriteria;        if(isset($_GET['date1'])&&isset($_GET['date2'])){            $criteria->addBetweenCondition('news_date',$_GET['date1'], $_GET['date2']);        }        //这个功能已经实现        //现在的问题是:如果用户只选择了 Date Form,就显示Date Form 这个日期之后的所有数据       // 只选择了 Date To就显示Date To 这个日期之前的所有数据                              return new CActiveDataProvider($this, array(            'criteria' => $criteria,        ));    }

public function failureCat()        {                $criteria = new CDbCriteria;                $criteria->compare('t.failItem', $this->failItem);                $criteria->compare('logInfo.logProcess', $this->failStation);                $criteria->compare('logInfo.logUpdate', '>=' . $this->dateToDatetime($this->startDate, 1));                $criteria->compare('logInfo.logUpdate', '<=' . $this->dateToDatetime($this->endDate));                $criteria->with = array('logInfo');                return new CActiveDataProvider('TestLogFail', array(                    'pagination' => array(                        'pageSize' => Yii::app()->params['pageSize'],                    ),                    'criteria' => $criteria,                    'sort' => array(                        'defaultOrder' => 'logInfo.logUpdate desc',                    ),                ));        }