SQL> update emp set sal = 1000;
14 rows updated.

SQL> update emp set sal = 500 where ename = 'KING';
1 row updated.

SQL> SELECT E.empno, E.ename, E.mgr, E.sal 
  2  FROM emp E
  3  WHERE empno IN (SELECT NVL(mgr, empno) FROM emp)
  4    AND NOT EXISTS
  5       (SELECT * FROM emp X
  6        WHERE X.sal < 950 -- условие по минимальной зарплате 
  7        CONNECT BY PRIOR X.empno = X.mgr
  8        START WITH X.mgr = E.empno)
  9  ;

     EMPNO ENAME             MGR        SAL
---------- ---------- ---------- ----------
      7566 JONES            7839       1000
      7698 BLAKE            7839       1000
      7782 CLARK            7839       1000
      7788 SCOTT            7566       1000
      7839 KING                         500
      7902 FORD             7566       1000
6 rows selected. 

SQL> ROLLBACK;
Rollback complete.