CI3.0框架中简单增删改查

第一步：模型层里有个控制器User_model.php里面内容为:
defined('BASEPATH') OR exit('No direct script access allowed');

class User_Model extends CI_Model
{
protected $table_name = "user";
//调用类库
public function __construct()
{
parent::__construct();
}
// //过滤字段
protected function filter_field($data){
$fields = $this->db->list_fields($this->table_name);//获取数据库字段
foreach($data as $key=>$val){
if(!in_array($key,$fields)){
unset($data[$key]);
}
}
return $data;
}
//添加
public function add($data){

    $data = $this->filter_field($data);
    $res = $this->db->insert($this->table_name,$data);
    if($res){
        return $this->db->insert_id();
    }else{
        return false;
    }
}

//CI 删除数据
public function delete($id)
{
return $this->db->delete('user', array('id' => $id));

}

//CI及点及改
public function status($id,$username,$password)
{
    $query = $this->db->where(array('id'=>$id))->update('user',array('username'=>$username,'password'=>$password));
    return $query;

}

//获取总条数
public function count()
{
    return $this->db->count_all_results($this->table_name);
}
//查看
public function select($offset)
{//读取配置每页显示条数
    return $this->db->get($this->table_name,$this->config->item('page_size'),$offset)->result_array();
}

//查询所有结果
public function getAll()
{
    return $this->db->get($this->table_name)->result_array();
}

//查询单条
public function getOne($id)
{
return $this->db->where(array('id'=>$id))->get($this->table_name)->row_array();

}

}
第二步：控制器里为:
defined('BASEPATH') OR exit('No direct script access allowed');

class Welcome extends CI_Controller {

/**
 * Index Page for this controller.
 *
 * Maps to the following URL
 *         http://example.com/index.php/welcome
 *    - or -
 *         http://example.com/index.php/welcome/index
 *    - or -
 * Since this controller is set as the default controller in
 * config/routes.php, it's displayed at http://example.com/
 *
 * So any other public methods not prefixed with an underscore will
 * map to /index.php/welcome/
 * @see https://codeigniter.com/user_guide/general/urls.html
 */
//构造函数
public function __construct()
{
    parent::__construct();
       $this->load->model('User_Model','user');
 
}
//表单添加页面
public function index()
{
    $this->load->view('index/welcome_message.html');
}
//执行添加
public function add()
{   

    $data = $this->input->post();
    $attr_id = $this->user->add($data);
    // print_r($data);die;

    if($attr_id)
    {   
        echo "";
    }
    else
    {   
        echo "";

    }

}
//查询
public function select()
{
    $data=$this->user->getAll();
    //print_r($data);die;
    $this->load->view('index/show.html',['date'=>$data]);
}
//删除
public function delete()
{
    $id=$_GET['id'];
    $res=$this->user->delete($id);
    if($res)
    {
      echo "";

    }
    else{
      echo "";

    }
}
//修改的数据
public function update()
{
    $id=$_GET['id'];
    $data=$this->user->getOne($id);
    $this->load->view('index/update.html',['data'=>$data]);
}
//执行修改
public function upd()
{   
    $id=$_POST['id'];
    $username=$_POST['username'];
    $password=$_POST['password'];
    $result=$this->user->status($id,$username,$password);
    if($result)
    {    
        echo "";

    }else{
        echo "";

    }
}

}

第三步:在views目录里新建index目录，分别是welcom_message.html show.html update.html.
其中welcom_message.html内容为:

用户名
密码

show.html里面内容为:

            $val) {?>
              

用户名	密码	操作
		删除||修改>

update.html内容为:

用户名
密码

注意:在配置目录/application/config/database.php中，1：$autoload['helper'] = array('url');

后面数组里面url一定得写上。
2：$autoload['libraries'] = array('database');

同理database也一定得写上