public function get_enrollments( $period = 'current' ) {

		global $wpdb;

		return $wpdb->get_var(
			$wpdb->prepare(
				"
			SELECT DISTINCT COUNT( user_id )
			FROM {$wpdb->prefix}lifterlms_user_postmeta
			WHERE meta_value = 'yes'
			  AND meta_key = '_start_date'
			  AND post_id = %d
			  AND updated_date BETWEEN %s AND %s
			",
				$this->post_id,
				$this->get_date( $period, 'start' ),
				$this->get_date( $period, 'end' )
			)
		);// db call ok; no-cache ok.

	}