SQL> update (
  2  select e.sal as emp_sal,e.comm as emp_comm,
  3     ns.sal as ns_sal, ns.sal/2 as ns_comm
  4  from emp e,new_sal ns
  5  where e.deptno=ns.deptno
  6  )set emp_sal=ns_sal,emp_comm=ns_comm;
)set emp_sal=ns_sal,emp_comm=ns_comm
     *
第 6 行出现错误:
ORA-01779: 无法修改与非键值保存表对应的列

SQL> select * from emp;

EMPNO ENAME     JOB         MGR HIREDATE        SAL      COMM DEPTNO
----- ---------- --------- ----- ------------ --------- --------- ------
 7369 SMITH      CLERK      7902 17-12月-80     1056.00               20
 7499 ALLEN      SALESMAN   7698 20-2月 -81     1600.00    300.00     30
 7521 WARD       SALESMAN   7698 22-2月 -81     1250.00    500.00     30
 7566 JONES      MANAGER    7839 02-4月 -81     3272.50               20
 7654 MARTIN     SALESMAN   7698 28-9月 -81     1250.00   1400.00     30
 7698 BLAKE      MANAGER    7839 01-5月 -81     2850.00               30
 7782 CLARK      MANAGER    7839 09-6月 -81     2450.00               10
 7788 SCOTT      ANALYST    7566 19-4月 -87     3960.00               20
 7839 KING       PRESIDENT       17-11月-81     5000.00               10
 7844 TURNER     SALESMAN   7698 08-9月 -81     1500.00       .00     30
 7876 ADAMS      CLERK      7788 23-5月 -87     1210.00               20

EMPNO ENAME     JOB         MGR HIREDATE        SAL      COMM DEPTNO
----- ---------- --------- ----- ------------ --------- --------- ------
 7900 JAMES      CLERK      7698 03-12月-81     1140.00               30
 7902 FORD       ANALYST    7566 03-12月-81     3300.00               20
 7934 MILLER     CLERK      7782 23-1月 -82     1560.00               10
 1111 YOUDA      JEDI            17-11月-81     5000.00
    1 JONATHAN     EDITOR

SQL> select * from new_sal;

      SAL DEPTNO
--------- ------
  4000.00     10

请大侠帮忙看看，我是菜鸟希望能说详细点。

alter table new_sal add constraintpk_new_sal primary key (deptno);