thinkphp 3.2 视图模型 查询 出来bool(false) 求解解决方法

thinkphp 3.2 视图模型 查询 出来bool(false) 求解
模型里这么写的

<?php<br />namespace Home\Model;<br />use Think\Model\ViewModel;<br />class PicViewModel extends  ViewModel{<br />    public $viewFields =array(<br />       'picture'=> array('picTitle','picToken','picCategroy','picAuthor','picPostTime','_type'=>'LEFT'),<br />        'picture_attachment' =>array('pictureid','pictureurl','creattime','_on'=>'picture.picToken = picture_attachment.pictureid'),<br /><br />    );<br />}

picture和picture_attachment两张表
控制器里这么写的 我用D方法实例化PicView 这个是必须在数据库里真实的表名么

    public function  Pic(){<br />         $PicModel =D('PicView');<br /><br />        dump($PicModel);<br />         $s =   $PicModel->select();<br />        dump($s);<br /><br />    }

返回的一些错误
["db":protected] => object(Think\Db\Driver\Mysql)#8 (19) {
["dbType":protected] => NULL
["autoFree":protected] => bool(false)
["model":protected] => string(7) "_think_"
["pconnect":protected] => bool(false)
["queryStr":protected] => string(0) ""
["modelSql":protected] => array(0) {
}
["lastInsID":protected] => NULL
["numRows":protected] => int(0)
["numCols":protected] => int(0)
["transTimes":protected] => int(0)
["error":protected] => string(0) ""
["linkID":protected] => array(0) {
}
["_linkID":protected] => NULL
["queryID":protected] => NULL
["connected":protected] => bool(false)
["autoinc":protected] => bool(false)
["patchValidate":protected] => bool(false)
------解决思路----------------------

<br /># PicView 模型初始化，如果该PicView类存在则调用并初始化，如果不存在 ，则根据表名初始化模型<br />         $PicModel =D('PicView');<br /> <br />#输出所有数据 实际执行的SQL语句是<br /># SELECT * FROM PicView<br />         $s =   $PicModel->select();<br />

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