ci框架libraries目录下自定义类操作数据库及调用方法

控制器调用方法：

$this->load->library('OrdContract');
$list=$this->ordcontract->get_zq_sales();


类代码：
<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Contract {

    public function __construct()
    {
        $this->MYCI = &get_instance();
       //$this->MYCI->db=$this->load->database();
        $this->MYCI->db=$this->MYCI->load->database('default', TRUE);
        $this->MYCI->load->model("OrdersModel");
        $this->MYCI->load->model("OrdersExtendModel");

        $this->tablename3 = 'user';
        $this->tablename4 = 'goods';

    }

    public function get_zq_sales(){
        $this->MYCI->load->model("SalesModel");
        $sale_guanli_arr=array();
        $sale_list=$this->MYCI->SalesModel->get_list(array('status'=>1),array(),'sid asc');
        foreach ($sale_list as $value){
            $sale_guanli_arr[$value['uid']]=$value['yqma'];
        }
        return $sale_guanli_arr;
    }

    public function zhongqian_contract_json_val_20889($zqid,$uid){

        $query1 = $this->MYCI->db->query("SELECT ct.*,kc.* FROM ".$this->tablename3." ct left join ".$this->tablename4." kc on ct.gid=kc.id WHERE ct.zqid=? and ct.uid=?",array($zqid,$uid));
        $contract_infos=$query1->row_array();
        P($contract_infos);
    }

}