发现自己没戏了 数据库分页显示 从数据库中选取第m到n行记录

前天去面试，被问到有关数据库分页显示的问题，以为答得还OK 搜了一下相关问题，发现自己没戏了。

数据库分页显示

首先要定义四个变量：

int pageSize:每页显示多少条记录

int pageNow:希望显示第几页

int pageCount:一共有多少页

int rowCount:一共有多少条记录

rowCount 通过 select count(*) from tableName 获得；

以下为oracle中例子，每页10条数据
select sendmethodids,remarks
from (select rownum num,sendmethodids, a remarks from test2）result2
where result2.num >= 1 and result2.num =< 10;

或者

select * from (select rownum r,all_objects.* from all_objects where rownum <=49) t where t.r >= 30;


若需要排序后再取每页数据，则需要多一层循环，如下

select sendmethodids,remarks
from (select rownum num,sendmethodids, a remarks
from (select sendmethodid sendmethodids,remark a
from test2 order by remark) result1) result2
where result2.num >= 1 and result2.num <= 10;

或者

select * from （select rownum r,all_objects.* from all_objects

where rownum <=49 order by object_id) t where t.r >= 30;

select * from (select * from a order by a.id) where rownum < = N

and a.id not in ( select * from (select * from a order by a.id)

where rownum<=M)

MySQL

select * from Tablename t order by t.F1 limit n,m-n+1

select * from DBtest t order by t.F1 limit 300000,20