三种常用数据库（Oracle、MySQL、SQLServer）分页

pageNow：当前第几页
pageSize：每页显示的记录数


MySQL分页：
select * from tableName limit (pageNow-1)*pagesize,pagesize



SQLServer分页：
select top pageSize * 
from tableName 
where id not in (select top  pageSize * (pageNow - 1) id from tableName);



Oracle分页：
select t.*
from(
  select rownum sn,te.*
  from tableName te
  where rownum <= pageSize * pageNow
)t where t.sn > num * (pageNow - 1);