一： oracle数据库写法：

    1：select * from (select rownum rn ,* from 表名 wher rownum<20) a

    where a.rn>10

    2：select * from 表名 where rownum<20

      minus

      select * from 表名 where rownum<10

      二：SqlServer数据库写法：

      1:select top 20 * from tablename where id not?exists (select top 10 * from tablename)//前20条记录再过滤掉前10条

      2:select top10 * from (select top 20 * from order by column) order by column desc//子查询中取20条倒序，然后从子查询中取前10条

      三：mysql的写法：

      select * from tablename where LIMIT 9,10