PHP Supplier

<?php
header('Access-Control-Allow-Origin: *');
header('Content-Type: application/json; charset=UTF-8');
header('Access-Control-Allow-Methods: POST, GET, DELETE, PUT');
header('Access-Control-Max-Age: 3600');
header('Access-Control-Allow-Headers: Content-Type, Access-Control-Allow-Headers, Authorization, X-Requested-With');

#BERI NAMA FILE DENGAN supplier-000.php

include 'database.php';
$db = new Database();

switch ($_SERVER['REQUEST_METHOD']) { //jenis method
    case 'POST':

        $db->open();

        switch ($_REQUEST['action']){
            case 'simpan':
                $sql = 'insert into supplier values("'. $_REQUEST['id'] .'", ';
                $sql .= '"'. $_REQUEST['nama'] .'", "'. $_REQUEST['alamat'] .'", ';
                $sql .= '"'. $_REQUEST['telp'] .'",  "'. $_REQUEST['email'] .'", ';
                $sql .= '"'. $_REQUEST['pic'] .'")';
                break;
            case 'ubah':
                $sql = 'update supplier set namasupplier = "'. $_REQUEST['nama'] .'", ';
                $sql .= 'alamatsupplier = "'. $_REQUEST['alamat'] .'", ';
                $sql .= 'telpsupplier = "'. $_REQUEST['telp'] .'", ';
                $sql .= 'emailsupplier = "'. $_REQUEST['email'] .'", ';
                $sql .= 'picsupplier = "'. $_REQUEST['pic'] .'" ';
                $sql .= 'where idsupplier = "'. $_REQUEST['id'] .'"';
                break;
            case 'hapus':
                $sql = 'delete from supplier where idsupplier ="'. $_REQUEST['id'] .'"';
                break;
        }

        $result = [
            'result' => $db->execute($sql)
        ];

        $db->close();
        print json_encode( $result );
        break;

    case 'GET':

        $db->open();

        $result = [
            'result' => $db->get('select * from supplier')
        ];

        $db->close();
        print json_encode( $result );
        break;

    default:

        http_response_code(400); //kode bad request

        $result = [
            'result' => null
        ];

        print json_encode( $result );
        break;
}
?>