1：批量删除回帖 pre_forum_post 表中存储的是论坛帖子和回复。每增加一个帖子或者回复，pid值+1. 
first值为1的，代表是主题。first值为0的，代表是回帖。 

delete from pre_forum_post where pid>3 and pid<16283795 and first=0; 

2：批量删除用户签名 

update pre_common_member_field_forum set sightml=''; 

3：批量删除N天前的用户短消息 

DELETE FROM pre_ucenter_pm_messages_0 WHERE dateline < 1353327620 ; 

时间戳可以从这里转换 http://tool.chinaz.com/Tools/unixtime.aspx 

4：调整某个帖子的点击数 

UPDATE cdb_threads SET views=点击数 WHERE tid=主题编号; 
UPDATE `cdb_forums` SET `allowmediacode` = '1' 
5：一次性关闭板块fid20帖子 

UPDATE `cdb_threads` SET `closed` = '1' WHERE `fid` =20 ;