Laravel框架如何实现model层的CURD操作

protected $table = 'user_city';public $timestamps = false;//添加 返回idpublic function cityadd($data){    return $this->insertGetId($data);}//单条查找public function getfind($id){    if($this->where('id',$id)->first()){      return $this->where('id',$id)->first()->toArray();    }else{      return [];    }}//查询用户有几个uid,返回数量public function countCity($uid){    if($this->where('uid',$uid)->first()){      return $this->where('uid',$uid)->count();    }else{      return [];    }}//查询全部数据public function getAll(){    return $this->get()->toArray();}/*** 修改管理员信息* @param $id* @param $data* @return bool*/public function upAdmin($id,$data){    if($this->find($id)){      return $this->where('id',$id)->update($data);    }else{      return false;    }}//加条件，时间//查询用户的认购的城数public function buy_num($uid){    $startDate = date('Y-m-01', strtotime(date("Y-m-d")));    $endDate = date('Y-m-d', strtotime("$startDate +1 month -1 day"));    // 将日期转换为Unix时间戳    $endDate=$endDate." 22:59:59";    $startDateStr = strtotime($startDate);    $endtDateStr = strtotime($endDate);    return $this->where('uid',$uid)->where('buy_type',1)->whereBetween('create_time', array($startDateStr,$endtDateStr))->sum('buy_num');}/*** 根据id查找城池信息 只返回某个字段的值* @param $id* @return array*/public function getCityName($id){    if($this->where('city_id',$id)->first()){      return $this->where('city_id',$id)->lists('city_name')[0];    }else{      return [];    }}