ขอความช่วยเหลื่อ codeigniter 3.0 กับ sqlsrv ครับ fullcalendar รันบน mysql ได้ปกติครับ แต่มีปัญหาบน sql server 2012

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Calendar_model extends CI_Model {


/*Read the data from DB */
	Public function getEvents()
	{
			/*$sql = $this->db->select('*')
 			->where('events.date', '$start')
 			->where('events.date', '$end' )
 			->order_by('events.date','asc')
 			->get('events');*/
		
	$sql = "SELECT * FROM events WHERE events.date BETWEEN ? AND ? ORDER BY events.date ASC";
	return $this->db->query($sql, array($_GET['start'], $_GET['end']))->result();

	}

/*Create new events */

	Public function addEvent()
	{
		$sql = array(
		'title' => $this->input->post('title'),
		'events.date' => $this->input->post('date'),
		'description' => $this->input->post('description'),		
		'color' => $this->input->post('color')
		);
	/*$sql = "INSERT INTO events (title,events.date, description, color) VALUES (?,?,?,?)";
	$this->db->query($sql, array($_POST['title'], $_POST['date'], $_POST['description'], $_POST['color']));*/
		
	/*$insert_status += $this->db->affected_rows();
	return $insert_status > 0 ? TRUE : FALSE;*/
	$this->db->insert('events',  $sql);
	return ($this->db->affected_rows()!=1)?false:true;
	}

	/*Update  event */

	Public function updateEvent()
	{
			$data = array(
            'title' => $this->input->post('title'),
			'events.date' => $this->input->post('date'),
			'description' => $this->input->post('description'),		
			'color' => $this->input->post('color')
            );
 
			$this->db->where('id', $id);
			$this->db->update('events', $data);

	/*$sql = "UPDATE events SET title = ?, events.date = ?, description = ?, color = ? WHERE id = ?";
	$this->db->query($sql, array($_POST['title'], $_POST['date'], $_POST['description'], $_POST['color'], $_POST['id']));*/
		return ($this->db->affected_rows()!=1)?false:true;
	}


	/*Delete event */

	Public function deleteEvent()
	{
		$this->db->delete('events', array('id' => $this->input->get('id')));
	/*$sql = "DELETE FROM events WHERE id = ?";
	$this->db->query($sql, array($_GET['id']));*/
		return ($this->db->affected_rows()!=1)?false:true;
	}

	/*Update  event */

	Public function dragUpdateEvent()
	{
			$date=date('Y-m-d h:i:s',strtotime($_POST['date']));

			$sql = "UPDATE events SET  events.date = ? WHERE id = ?";
			$this->db->query($sql, array($date, $_POST['id']));
		return ($this->db->affected_rows()!=1)?false:true;


	}
}
?>

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Calendar extends CI_Controller {

		function __construct()
    {
        // Call the Model constructor
        parent::__construct();

        $this->load->model('Calendar_model');
    }


	/*Home page Calendar view  */
	Public function index()
	{
		$this->load->view('home');
	}

	/*Get all Events */

	Public function getEvents()
	{
		$result=$this->Calendar_model->getEvents();
		echo json_encode($result);
	}
	/*Add new event */
	Public function addEvent()
	{
		$result=$this->Calendar_model->addEvent();
		echo $result;
	}
	/*Update Event */
	Public function updateEvent()
	{
		$result=$this->Calendar_model->updateEvent();
		echo $result;
	}
	/*Delete Event*/
	Public function deleteEvent()
	{
		$result=$this->Calendar_model->deleteEvent();
		echo $result;
	}
	Public function dragUpdateEvent()
	{	

		$result=$this->Calendar_model->dragUpdateEvent();
		echo $result;
	}
}