code: function delete(){
          if($this->notORM->freeze){
              return false;
          }
          //防止误删，禁止全表的删除
          //@dogstar - 2014-10-24
          $where = $this->whereString();
          if(empty($where)){
              throw new Exception('sorry, you can not delete the whole table --dogstar');
          }
  
          $return = $this->query("DELETE" . $this->topString($this->limit) . " FROM $this->table" . $where, $this->parameters);
          if(!$return){
              return false;
          }
          return $return->rowCount();
      }
docs: Delete all rows in result set
  @return bool|int number of affected rows or false in case of an error
  @throws Exception