oracle数据库查询前几条数据

Posted 2023-03-23

参考技术A

选取列表的前三行：

select * from 表A where rownum <= 3;

Oracle查询前几条数据的方法

由于Oracle不支持select top 语句，所以在Oracle中经常是用order by 跟rownum的组合来实现select top n的查询。简单地说，实现方法如下所示：select 列名1 ...列名n from(select 列名1 ...列名nfrom 表名 order by 列名1)where rownum <=N(抽出记录数)order by rownum asc如：select id,name from (select id,name from student order by name) where rownum<=10 order by rownum asc按姓名排序取出前十条数据附：取100-150条数据的方法1.最佳选择：利用分析函数row_number() over ( partition by col1 order by col2 )比如想取出100-150条记录,按照tname排序select tname,tabtype from (select tname,tabtype,row_number() over ( order by tname ) rn from tab) where rn between 100 and 150;2. 使用rownum 虚列select tname,tabtype from (select tname,tabtype,rownum rn from tab 参考技术A 由于Oracle不支持select top 语句，所以在Oracle中经常是用order by 跟rownum
的组合来实现select top n的查询。
简单地说，实现方法如下所示：
select 列名1 ...列名n from(select 列名1 ...列名n
from 表名 order by 列名1)where rownum <=N(抽出记录数)
order by rownum asc
如：select id,name from (select id,name from student order by name) where rownum<=10 order by rownum asc
按姓名排序取出前十条数据
附：取100-150条数据的方法1.
最佳选择：利用分析函数
row_number() over ( partition by col1 order by col2 )比如想取出100-150条记录,按照tname排序
select tname,tabtype from (
select tname,tabtype,row_number() over ( order by tname ) rn from tab
) where rn between 100 and 150;
2. 使用rownum 虚列
select tname,tabtype from (
select tname,tabtype,rownum rn from tab