oracle 分页 sql

select * 
from
(select * from (select t.*, rownum linenum from gal_messages t) r where r.linenum <200) a
where a.linenum>100

Note: 一定要给rownum一个别名linenum, 否则r.rownum或a.rownum会出错.

Oracle Connect By用法
参照：http://www.cublog.cn/u1/54706/showart_1711812.html
oracle中的select语句可以用START WITH...CONNECT BY PRIOR子句实现递归查询，connect by 是结构化查询中用到的，其基本语法是：

select ... from <TableName>
where <Conditional-1>
start with <Conditional-2>
connect by <Conditional-3>
;

<Conditional-1>：过滤条件，用于对返回的所有记录进行过滤。
<Conditional-2>：查询结果重起始根结点的限定条件。
<Conditional-3>：连接条件

数据库表结构如下：

create table t2(
root_id number,
id number,
name varchar(5),
description varchar(10)
);

insert into t2(root_id,id,name,description) values(0,1,'a','aaa');
insert into t2(root_id,id,name,description) values(1,2,'a1','aaa1');
insert into t2(root_id,id,name,description) values(1,3,'a2','aaa2');
insert into t2(root_id,id,name,description) values(0,4,'b','bbb');
insert into t2(root_id,id,name,description) values(4,5,'b1','bbb1');
insert into t2(root_id,id,name,description) values(4,6,'b2','bbb2');

获取完整树：

select * from t2 start with root_id = 0 connect by prior id = root_id;

查询结果: 所有记录

获取特定子树：

select * from t2 start with id = 1 connect by prior id = root_id;

查询结果:
root_id   id
0         1
1         2
1         3

select * from t2 start with id = 4 connect by prior id = root_id;

root_id   id
0         4
4         5
4         6

如果connect by prior中的prior被省略，则查询将不进行深层递归。
For example:

select * from t2 start with root_id = 0 connect by id = root_id;

root_id   id
0         1
0         4

select * from t2 start with id = 1 connect by id = root_id;

root_id   id
0         1