pl/sql有关问题

pl/sql问题
一张dept表怎么取前五个？

------解决方案--------------------
rownum <=5
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需要按照某条件排序不？

不需要，则：
select * from dept where rownum<=5;

需要，则：
select * from (select select t.*, ROWNUM rn from dept order by xxx asc|desc)
where rn<=5
------解决方案--------------------
select * from dept where rowid<6
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SQL code

select * from dept where rownum <=5;
------解决方案--------------------
探讨


需要，则：
select * from (select select t.*, ROWNUM rn from dept order by xxx asc|desc)
where rn <=5