SELECT * FROM your_table WHERE rownum = 1

SELECT * FROM (SELECT * FROM your_table
               ORDER BY DBMS_RANDOM.VALUE
              )
WHERE rownum = 1;

select * 
from(  select * 
       from employees
       order by dbms_random.value
     )
 where rownum =1

select * from mytable sample block (1) where rownum = 1;

from(  select * 
       from employees
       order by dbms_random.value
     )
 where rownum =1

select * 
from (select * from mytable sample(1))
where rownum = 1;

SQL> select *
  2  from (select * from employees sample(1))
  3  where rownum = 1;

EMPLOYEE_ID FIRST_NAME           LAST_NAME
----------- -------------------- -------------------------
EMAIL                     PHONE_NUMBER         HIRE_DATE JOB_ID         SALARY
------------------------- -------------------- --------- ---------- ----------
COMMISSION_PCT MANAGER_ID DEPARTMENT_ID          X
-------------- ---------- ------------- ----------
        116 Shelli               Baida
SBAIDA                    515.127.4563         24-DEC-97 PU_CLERK         2900
                      114            30


SQL> /

no rows selected

SELECT * FROM EMP SAMPLE(1)