1 create database test;
2 use test;
3 create table user(
4     id int(10) not null auto_increment,
5     name varchar(50) not null,
6     age int(10) not null,
7     primary key (id)
8 );

 1 <?php
 2
 3 class User_Model extends CI_Model
 4 {
 5
 6     function __construct()
 7     {
 8         parent::__construct();
 9         // connect to the database
10         $this->load->database();
11     }
12
13     function user_insert($arr)
14     {
15         $this->db->insert('user', $arr);
16     }
17
18     function user_update($id, $arr)
19     {
20         $this->db->where('id', $id);
21         $this->db->update('user', $arr);
22     }
23
24     function user_delete($id)
25     {
26         $this->db->where('id', $id);
27         $this->db->delete('user');
28     }
29
30     function user_select($id)
31     {
32         $this->db->where('id', $id);
33         $this->db->select('*');
34         $query = $this->db->get('user');
35         return $query->result();
36     }
37 }

 1 <?php
 2
 3 class User extends CI_Controller
 4 {
 5     public function insert()
 6     {
 7         $this->load->model('user_model');
 8         $arr = array('name'=>'aaa', 'age'=>16);
 9         $this->user_model->user_insert($arr);
10     }
11
12     public function update()
13     {
14         $this->load->model('user_model');
15         $arr = array('id'=>2, 'name'=>'bbb','age'=>23);
16         $this->user_model->user_update(2, $arr);
17     }
18
19     public function delete($id)
20     {
21         $this->load->model('user_model');
22         $this->user_model->user_delete($id);
23     }
24
25     public function select()
26     {
27         $this->load->model('user_model');
28         $arr = $this->user_model->user_select(1);
29         print_r($arr);
30     }
31 }