有时候会用到查询倒数第二条记录
last=HolderChangeHistory.find_by_sql([" SELECT * FROM holder_change_histories where treasure_id = ? order by id desc limit 1,1 ", @hch.treasure_id])
select * from tablename a where ( select count(*) from tablename b where a.id<b.id)=1
select * from tb1 order by tb1.id desc limit 1,1;
