Oracle--分页

1、分页查询

 

oracle分页一共有三种

1、rownum分页

    （select * from emp）

2、显示rownum[oracle分配的]

    select a1.*,rownum rn from (select * from emp) a1;

3、

    按雇员的id号升序取出

select a1.* ,rownum rn from (select * from emp) a1;

 

    取出编号10以下的雇员

select a1.*,rownum rn from (select * from emp) a1,where rownum<=10;

 

    取出编号6-10的雇员

select * from (select a1.*,rownum rn from (select * from emp) a1 where rownum<=10) where rn<=6;

 

4、几个查询变化

①指定查询列，只需修改最里层的子查询

select * from (select a1.*,rownum rn from (select ename,sal from emp) a1 where rownum<=10) where rn>=6;

②如何排序，只需修改最里层的子查询

select * from (select a1.*,rownum rn from (select ename,sal from emp order by sal) a1 where rownum<=10) where rn>=6;

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1、根据ROWID来分

select * from t_xiaoxi where rowid in (select rid from (select rownum rn,rid from (select rowid rid,cid from t_xiaoxi order by cid desc) where rownum<10000) where rn>9980) order by desc;

执行时间0.03s

2、按分析函数来分

select * from (select t.*,row_number() over(order by cid desc) rk from t_xiaoxi t) where rk<10000 and rk>9980;

执行时间1.01s

3、按ROWNUM来分

select * from (select t.*,rownum rn from (select * from t_xiaoxi order by cid desc) t where rownum<10000) where rn>9980;

执行时间0.1s

 

其中t_xiaoxi为表名称，cid为表的关键字段，取按CID降序排序后的第9981-9999条记录，t_xiaoxi表有70000多条记录

 

//测试通过的分页查询

select * from (select a1.*,rownum rn from (select ename,job from emp) a1 where rownum<=10) where rn>=5;