以medoo框架为例http://medoo.lvtao.net/

app/ctrl/indexCtrl.php

<?php
namespace app\ctrl;

use app\model\admin_userMoel;

class indexCtrl extends \core\xxt
{
    public function index()
    {
        $model = new admin_userMoel();//new一个admin_uswerModel模型对象
        $id = isset($_GET['id'])?$_GET['id']:'1';
        $ret = $model->getOne($id);
        $this->assign('admin_user', $ret);
        $this->display('index.html');
//        dump($ret);
    }
}

app/model/admin_userModel.php

<?php
namespace app\model;

use core\lib\model;

class admin_userMoel extends model
{
    public $table = 'admin_user';

    public function lists()
    {
        $ret = $this->select($this->table,'*');
        return $ret;
    }

    public function getOne($id)
    {
        $ret = $this->get($this->table,'*',array('id' => $id));
        return $ret;
    }

    public function setOne($id,$data)
    {
        $this->update($this->table,$data,array('id' => $id));
        return $this->id();
    }

    public function delOne($id)
    {
        $this->delete($this->table,array('id' => $id));
        return $this->id();
    }

}

core/lib/model.php

<?php
namespace core\lib;
use core\lib\conf;
class model extends \Medoo\Medoo
{
    public function __construct()
    {
        $option = conf::all('database');
        parent::__construct($option);//调用父类构造函数，初始化数据库对象
    }
}