Oracle update和order by

今天遇到一个关于SQL转换成Oracle语句的问题，描述如下：

select * from emp order by deptno;

select * from dept;

Sql Server:

update dept a set dname=(select top 1 ename from emp where deptno=a.deptno order by sal)

经过尝试，查找资料，得出下面转换结果，不知道这样是否可行：

update dept a set dname=

(with t as(select ename,deptno from emp order by sal)

select ename from t where deptno=a.deptno and rownum=1)

where exists(with t as(select ename,deptno from emp order by sal)

select null from t where deptno=a.deptno)

执行结果：

select * from dept;

其他替代方法随后再做尝试。