function dozent_instructor_attach_course( $course = null, $user = null ) {
		global $wpdb;

		$course = get_post( $course );
		$user   = dozent_get_the_user( $user );

		if ( ! dozent_instructor_is_attached_to_course( $course, $user ) ) {

			$data = apply_filters( 'dozent_instructor_attach_course_data', [
				'course_id' => $course->ID,
				'instructor_id'   => $user->ID,
				'added_at'  => current_time( 'mysql' ),
			] );


			/**
			 * Action hook before attach an instructor to a specific course
			 *
			 * @since DozentLMS 1.0.0
			 *
			 * @param array $data Inserted data
			 * @param object $user User Object
			 * @param object $course Course | Post Object
			 */

			do_action( 'dozent_instructor_attach_course_before', $data, $user, $course );

			$inserted = $wpdb->insert( $wpdb->dozent_instructor_courses, $data );

			if ( $inserted ){
				$inserted_id = (int) $wpdb->insert_id;

				/**
				 * Action hook after attach an instructor to a specific course
				 *
				 * @since DozentLMS 1.0.0
				 *
				 * @param int $inserted_id Inserted Row ID
				 * @param array $data Inserted data
				 * @param object $user User Object
				 * @param object $course Course | Post Object
				 */

				do_action( 'dozent_instructor_attach_course_after', $inserted_id, $data, $user, $course );


				return $inserted_id;
			}
		}

		return false;
	}