1.ROWID伪劣
唯一地址编号
2.ROWNUM伪劣
自动生成行号
分页的时候用到
select rownum rn,* from dual;
查询分页的语句
SELECT * FROM (
SELECT ROWNUM rn,a.* FROM (
SELECT * FROM SYS_MENU ORDER BY M_SORTCODE
) a where ROWNUM<=(page*pagesize)
) s WHERE s.rn>(page-1)*pagesize
oracle 12c以后新特性fetch
(1)取得前N行记录:fetch first 行数 row only
select * from emp fetch first 5 row only;取得前5行记录
(2)取得指定范围的记录:offset 开始位置 rows fetch next 个数 rows only; 所有行的记录是从0开始,类似于mysql的limit分页
select * from enm order by sal desc offset 2rows fetch next 5 rows only;
(3)按照百分比取得记录 fetch next 百分比 fercent rows only;
select * from emp order by sal desc fetch 10 percent rows only;