select e.last_name, ee.last_name
from employees e join employees ee on (e.manager_id = ee.employee_id)
where last_name in (select last_name
from employees
where employee_id in (select distinct manager_id
from employees
)
);
答案 0 :(得分:1)
如果我对您的理解正确,则只希望选择经理。
以下示例基于Scott的模式。
这里是所有员工,以及他们的经理(按层次划分),因此更容易发现经理。
SQL> select lpad(' ', (level - 1) * 2) || ename ename
2 from emp
3 start with mgr is null
4 connect by prior empno = mgr;
ENAME
------------------------------------------------------
KING -- manager
JONES -- manager
FORD -- manager
SMITH -- employee
BLAKE -- manager
ALLEN -- employee
WARD -- employee
MARTIN -- employee
TURNER -- employee
JAMES -- employee
CLARK -- manager
MILLER -- employee
12 rows selected.
SQL>
附加WHERE
子句仅返回管理者:
SQL> select lpad(' ', (level - 1) * 2) || ename ename
2 from emp
3 where empno in (select mgr from emp)
4 start with mgr is null
5 connect by prior empno = mgr;
ENAME
--------------------------------------------------------
KING
JONES
FORD
BLAKE
CLARK
SQL>
用SYS_CONNECT_BY_PATH
替换 ,我们将获得不同的输出:
SQL> select sys_connect_by_path(ename, ' / ') path
2 from emp
3 where empno in (select mgr from emp)
4 start with mgr is null
5 connect by prior empno = mgr;
PATH
----------------------------------------------------
/ KING
/ KING / JONES
/ KING / JONES / FORD
/ KING / BLAKE
/ KING / CLARK
SQL>
或者按照您的步骤,通过EMP
表的自联接,我们得到
SQL> select m1.ename manager, m2.ename his_manager
2 from emp m1 join emp m2 on m1.mgr = m2.empno
3 where m1.empno in (select mgr from emp);
MANAGER HIS_MANAGER
---------- -------------
FORD JONES
CLARK KING
BLAKE KING
JONES KING
SQL>
选择最适合您的一个。我相信其他成员会建议其他选择。