From PHPBB用户手册

# Table: 'phpbb_topics_watch'
CREATE TABLE phpbb_topics_watch (
	topic_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, 主题ID
	user_id mediumint(8) UNSIGNED DEFAULT '0' NOT NULL, watch这个主题的用户ID
	notify_status tinyint(1) UNSIGNED DEFAULT '0' NOT NULL, 通知状态
	KEY topic_id (topic_id),
	KEY user_id (user_id),
	KEY notify_stat (notify_status)
) CHARACTER SET `utf8` COLLATE `utf8_bin`;