Include php on a specific page template

WordPress had a built-in conditional tag for that:

if ( is_page_template( 'page-courses.php' ) ) {
     include_once('functions_courses.php');
};

More infos on the codex

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)