class studCredController extends CI_Controller {

     public function __construct()
{
    parent::__construct();
    $this->load->database();
    //load Model
    $this->load->model('studCredModeller');
}
    //Register students
    public function registerStud() {

    //load registration view form
    $this->load->view('Home');

    //Check the submit button
    if($this->input->post('save'))
    {
        $username = $this -> input -> post('username');
        $email = $this -> input -> post('email');
        $password = $this -> input -> post('password');
        $admin_no = $this -> input -> post('adminNo');
        $phone = $this -> input -> post('phone');

        //call method of studCredModeller and pass variable as parameter
        $this -> studCredModeller -> saveRecords($username, $email, $password, $admin_no, $phone);
        echo "Records Saved Successfully";

        }
    }
}

class studCredModeller extends CI_Model
    {
        public function saveRecords($username, $email, $password, $adminNo, $phone);
        {
            $query="insert into locka.stud_login values('$username','$email','$password','$admin_no','$phone', ' ')";
            $this->db->query($query);
    }
    }

<form method="post">
                    <div class="row">
                      <div class="col-xs-6 col-sm-6 col-md-6">
                        <div class="form-group">
                          <label>Username</label>
                          <input type="text" class="form-control" name="username" placeholder="Username">

                        </div>
                      </div>
                      <div class="col-xs-6 col-sm-6 col-md-6">
                        <div class="form-group">
                         <label>Email</label>
                        <input type="email" class="form-control" name="email" placeholder="Email">
                    </div>
                      </div>
                      </div>
                       <div class="row">
                      <div class="col-xs-6 col-sm-6 col-md-6">
                      <div class="form-group">
                    <label>Password</label>
                    <input type="password" class="form-control" name="password" placeholder="Password">
                    </div>
                    </div>

                      <div class="col-xs-6 col-sm-6 col-md-6">
                        <div class="form-group">
                          <label>Admin No</label>
                              <input type="text" class="form-control" name="adminNo" placeholder="AdminNo">

                        </div>
                      </div>
                      <div class="col-xs-6 col-sm-6 col-md-6">
                        <div class="form-group">
                          <label>Phone number</label>
                           <input type="number" class="form-control" name="phone" placeholder="Phone">

                        </div>
                      </div>
                       </div>

                    <input type="submit" value="Submit" name="save" class="btn btn-skin btn-block btn-lg">

                    <p class="lead-footer">* We'll contact you by phone & email later</p>


                  </form>