秋天，那永远是蓝湛湛的天空，会突然翻脸而露出险恶的颜色，热带台风夹着密云暴雨，洪水潜流着，复苏的草原又泛起点点苍苍的颜色。然而，台风暴雨一闪而过，强烈的气流依然抖动着耀眼的波光。这时，只有北来的候鸟知道这张温暖的床眠，那飞翔的天鹅、鸿雁和野鸭，就像一片阴深的云朵，使这儿显得更苍郁了。
第一步：我先用rownum --分页 row_number，不是rownum
create table T_NEWS
(
ID NUMBER,
N_TYPE VARCHAR2(20),
N_TITLE VARCHAR2(30),
N_COUNT NUMBER
) prompt Disabling triggers for T_NEWS...
alter table T_NEWS disable all triggers;
prompt Loading T_NEWS...
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (1, 'IT', '爱it1', 100);
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (2, '体育', '爱体育1', 10);
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (3, '体育', '爱体育2', 30);
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (4, 'IT', '爱it2', 300);
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (5, 'IT', '爱it3', 200);
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (6, '体育', '爱体育3', 20);
insert into T_NEWS (ID, N_TYPE, N_TITLE, N_COUNT)
values (7, '体育', '爱体育4', 60);
commit;
--根据n_count从大到小排列，每页3条
SELECT ROWNUM r,t.* FROM t_news t
WHERE ROWNUM<=3
ORDER BY t.n_count DESC
--问题：为什么order by以后，行号是乱的？
SELECT ROWNUM r,t.* FROM t_news t
--原因：先分配了行号，再根据n_count排序 --所以必须排序，再生成行号
SELECT ROWNUM r,t.* FROM (
SELECT t.* FROM t_news t ORDER BY t.n_count DESC ) t --分页
--err
SELECT ROWNUM r,t.* FROM (
SELECT t.* FROM t_news t ORDER BY t.n_count DESC ) t
WHERE r between 1 AND 3 --第1页
SELECT ROWNUM r,t.* FROM (
SELECT t.* FROM t_news t ORDER BY t.n_count DESC ) t
WHERE ROWNUM between 1 AND 3 --第2页
SELECT ROWNUM r,t.* FROM (
SELECT t.* FROM t_news t ORDER BY t.n_count DESC ) t
WHERE ROWNUM between 4 AND 6
--error: ROWNUM必须从1开始！
SELECT k.* FROM (
SELECT ROWNUM r,t.* FROM (
SELECT t.* FROM t_news t ORDER BY t.n_count DESC ) t
) k
WHERE r BETWEEN 4 AND 6 --麻烦，效率低！
*****第二步:我用row_number() over()函数
select t2.* from
(select t.*,row_number()over(order by t.n_count desc) orderNumber from t_news t order by t.n_count desc)t2 where orderNumber between 1and 3;
*****************************************************************************************************************************************88
SELECT * FROM (
SELECT t.*,row_number() over(ORDER BY n_count DESC) r
FROM t_news t
ORDER BY t.n_count DESC
) t
WHERE r BETWEEN 4 AND 6 --通用语法： 解析函数() over(partition by 字段 order by 字段)
以上就是Oraclerow_number()over()解析函数高效如何实现分页。有些人仅仅只是我们生命中一个过客，来无痕去无迹；有些人有缘相守一辈子，却在心里激不起一丝波澜，寡淡无味；有些人仅仅就看了一眼，却在心底从此生根，甚至牵念一生。更多关于Oraclerow_number()over()解析函数高效如何实现分页请关注haodaima.com其它相关文章！