CodeIgniter数据库操作教程与实例解析

$db['default'] = array(
    'dsn'      => '',
    'hostname' => 'localhost',
    'username' => 'root',
    'password' => 'your_password',
    'database' => 'your_database',
    'dbdriver' => 'mysqli',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci'
);

$this->load->database();

$autoload['libraries'] = array('database');

$query = $this->db->query("SELECT * FROM users WHERE age > 20");
foreach ($query->result() as $row) {
    echo $row->name;
}

• $this->db->get()：获取整张表数据
• $this->db->where()：添加条件
• $this->db->result()：返回对象数组
• $this->db->row()：返回单个对象

$query = $this->db->get('users'); // SELECT * FROM users
$query = $this->db->where('id', 5)->get('users'); // SELECT * FROM users WHERE id = 5
$user = $query->row(); // 获取单条记录

$data = array(
    'name' => '张三',
    'email' => 'zhangsan@example.com',
    'age' => 25
);
$this->db->insert('users', $data); // INSERT INTO users SET ...
echo $this->db->insert_id(); // 获取最后插入的 ID

$data = array(
    'name' => '李四',
    'age' => 26
);
$this->db->where('id', 5);
$this->db->update('users', $data); // UPDATE users SET ... WHERE id = 5

$this->db->where('id', 5);
$this->db->delete('users'); // DELETE FROM users WHERE id = 5

$result = $this->db
    ->select('id, name, email')
    ->from('users')
    ->where('status', 1)
    ->limit(10)
    ->get()
    ->result();

class User_model extends CI_Model {
    public function get_users($status = 1) {
        return $this->db->where('status', $status)->get('users')->result();
    }
public function insert_user($data) {
    $this->db->insert('users', $data);
    return $this->db->insert_id();
}
}

$this->load->model('User_model');
$users = $this->User_model->get_users();