在model层写了一个查询语句结果报错  Fatal error: Class 'think\db' not found  

 $list= Db::table('m_my_reserve_assess')

            ->alias('mra')

             ->field('mra.id,mra.insert_time,mra.update_time,mra.status,ma.realname,c.company_name,u.name,u.mobile')

            ->join('m_user u','mra.uid = u.id')

            ->join('m_my_reserve mr','mra.mr_id = mr.id')

            ->join('m_company c','mr.r_cid = c.id')

            ->join('m_admin ma','mra.aid = ma.id')

           ->where($where)

           ->order(['mra.insert_time'=>'desc', 'mra.update_time' => 'desc'])

           ->select();

刚开始以为是

Class 'think\db'没有引用，然后实际情况是有引用的。

解决办法

在前面实例化这个model就行

 $MyReserveAssess = new MyReserveAssess();

//        $list=$MyReserveAssess

       $list= Db::table('m_my_reserve_assess')

            ->alias('mra')

             ->field('mra.id,mra.insert_time,mra.update_time,mra.status,ma.realname,c.company_name,u.name,u.mobile')

            ->join('m_user u','mra.uid = u.id')

            ->join('m_my_reserve mr','mra.mr_id = mr.id')

            ->join('m_company c','mr.r_cid = c.id')

            ->join('m_admin ma','mra.aid = ma.id')

           ->where($where)

           ->order(['mra.insert_time'=>'desc', 'mra.update_time' => 'desc'])

           ->select();