A,B,C三表连表查询：A.bid=B.id,b.cid = c.id
A模型的relations中：
'packing_order'=>array(
self::BELONGS_TO,
'B',
['a.bid' => 'b.id']，
'with'=>'B模型中的relations_name'
),
B的模型relations中：
'relations_name'=>array(
self::BELONGS_TO,
'C',
['b.cid' => 'c.id']
),
***************************************************************************
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(
'packing_order'=>array(
self::BELONGS_TO,
'PackingOrder',
['packing_order_id' => 'id'],
'select'=>'packing,supplier,number,code'
),
);
}
************************************************************************
$criteria= new CDbCriteria();
$criteria->join = 'LEFT JOIN oa_packing_order as po ON po.id=t.packing_order_id LEFT JOIN oa_packing_material as pm ON po.packingid=pm.id';
$criteria->select = "t.*,pm.type,po.packing,po.supplier,po.number,po.code";
$criteria->addCondition("查询条件");
$criteria->order = $order = '排序方法';
$model = Reports::model()->findAll($criteria);
