SQL statement/php

i got an unidentified index error in this line 6 and 7 please help

<?php if( ! defined( 'ACCESS' ) ) die( 'DIRECT ACCESS NOT ALLOWED' ); ?>
<?php

if( isset( $_POST ) ) {

$name = $_POST[ 'name' ];
$id = $_POST[ 'id' ];

if( $DB->query( "UPDATE products SET name='$name' WHERE id=$id" ) ) {
$MESSAGE = "Product successfully updated!";
$MESSAGE_TYPE = "info";
} else {
$MESSAGE = "Failed to update Product";
$MESSAGE_TYPE = "danger";
}

}