利用over开窗函数取第一条记录

SQL> set linesize 200
SQL> select * from (select a.* ,row_number() over( order by empno) rn  from emp a)
where rn=1  2 
  3  ;

     EMPNO ENAME      JOB        MGR HIREDATE     SAL       COMM     DEPTNO DNAME        RN
---------- ---------- --------- ---------- --------- ---------- ---------- ---------- -------------------------------------------------- ----------
      7369 SMITH      CLERK       7902 17-DEC-80     800      20 UFO