[转]oracle 12c 中的分页子句

转自：http://blog.itpub.net/271063/viewspace-1061279/

-- 连接数据库 创建测试用户
-- Connected to Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 
-- Connected as system@al32_192.168.56.120

create user scott identified by tiger default tablespace users;
grant connect,resource to scott;
grant unlimited tablespace to scott;

-- 创建测试表
create table big_table
as
select rownum id, a.*
  from all_objects a
 where 1=0
/
alter table big_table nologging;

-- 添加200万测试记录
declare
    l_cnt number;
    l_rows number := &1;
begin
    insert /*+ append */
    into big_table
    select rownum, a.*
      from all_objects a
     where rownum <= &1;
    l_cnt := sql%rowcount;
    commit;
    while (l_cnt < l_rows)
    loop
        insert /*+ APPEND */ into big_table
        select rownum+l_cnt, 
               OWNER, OBJECT_NAME, SUBOBJECT_NAME, OBJECT_ID, DATA_OBJECT_ID,
               OBJECT_TYPE, CREATED, LAST_DDL_TIME, TIMESTAMP, STATUS,
               TEMPORARY, GENERATED, SECONDARY, NAMESPACE, EDITION_NAME,
               SHARING,EDITIONABLE,ORACLE_MAINTAINED  
          from big_table
         where rownum <= l_rows-l_cnt;
        l_cnt := l_cnt + sql%rowcount;
        commit;
    end loop;
end;
/
alter table big_table add constraint big_table_pk primary key(id);
exec dbms_stats.gather_table_stats( user, 'BIG_TABLE', estimate_percent=> 1);

-- 查看占用磁盘空间大约280兆
SQL> select 35862*8 from dual;
   35862*8
----------
    286896

-- 开始使用oracle自带的分页子句，去前三条记录。
SQL> set timing on
SQL> 
SQL> select id,object_name from big_table
  2  order by id fetch first 3 rows only ;
        ID OBJECT_NAME
---------- --------------------------------------------------------------------------------
         1 ORA$BASE
         2 DUAL
         3 DUAL
Executed in 0.531 seconds

SQL> select id,object_name from big_table
  2  order by id
  3  offset 3 rows fetch next 3 rows only;
        ID OBJECT_NAME
---------- --------------------------------------------------------------------------------
         4 MAP_OBJECT
         5 SYSTEM_PRIVILEGE_MAP
         6 SYSTEM_PRIVILEGE_MAP
Executed in 0.407 seconds

SQL> select id,object_name from big_table
  2  order by id
  3  offset 6 rows fetch next 3 rows only;
        ID OBJECT_NAME
---------- --------------------------------------------------------------------------------
         7 TABLE_PRIVILEGE_MAP
         8 TABLE_PRIVILEGE_MAP
         9 USER_PRIVILEGE_MAP
Executed in 0.406 seconds

SQL> select id,object_name from big_table order by id
  2  offset 0 rows fetch next 3 rows only;
        ID OBJECT_NAME
---------- --------------------------------------------------------------------------------
         1 ORA$BASE
         2 DUAL
         3 DUAL
Executed in 0.406 seconds

SQL>

在省厅查人时，可以使用这项技术。原来离不了rownum. IBATIS是否有适应oracle12c的设置呢？