我需要一個遞歸查詢來獲得在oracle中的計算字段

Question

我不知道什麼最好的方法是獲得我要找的結果。在一個oracle 10g數據庫中，我試圖查詢所有用戶，併爲每個有主管人員的行生成一個計算字段，如果他們的主管類型是U.如果不是，我需要走到樹上直到找到一個。這個查詢可能需要遞增多個級別。

所以對於一個Employee表是這樣的：

Employee Table 
+-------+----------+--------------+---------------+ 
| empno | empgroup |  user  | supervisor_no | 
+-------+----------+--------------+---------------+ 
|  1 | E  | Joe Schmo |    4 | 
|  2 | E  | Mark Marin |    3 | 
|  3 | U  | Reed Patter |    7 | 
|  4 | E  | Martin Price |    7 | 
|  7 | U  | Mary Wengert |    | 
+-------+----------+--------------+---------------+ 

我希望看到這樣的結果，其中manager_no將計算出的字段

Results 
+-------+----------+--------------+---------------+------------+ 
| empno | empgroup |  user  | supervisor_no | Manager_No | 
+-------+----------+--------------+---------------+------------+ 
|  1 | E  | Joe Schmo |    4 |   7 | 
|  2 | E  | Mark Marin |    3 |   3 | 
|  3 | U  | Reed Patter |    7 |   7 | 
|  4 | E  | Martin Price |    7 |   7 | 
|  7 | U  | Mary Wengert |    |   | 
+-------+----------+--------------+---------------+------------+ 

好了，所以我一直在問我試過。我並不是說這是必須這樣做的方式，如果有人有更好的建議，我全都是耳朵，但這是我想要實現的。

我想象了兩部分。

select * from employee em 
connect by prior supervisor_no = empno 
start with empno = 1 

[結果] [2]：即得到所有我的結果

select em.empno, em.empgroup, em.user, em.supervisor, (my subquery) as manager_no 
from employee em 

查詢主查詢

| EMPNO | EMPGROUP |  USERNAME | SUPERVISOR_NO | 
--------------------------------------------------- 
|  1 |  E | Joe Schmo |    4 | 
|  4 |  E | Martin Price |    7 | 
|  7 |  U | Mary Wengert |  (null) | 

好吧，我找到了一種方法來篩選對可能工作的團隊，但不知道這是否是最有效的路線。

SELECT empno FROM (
SELECT empno FROM employee em 
CONNECT BY PRIOR supervisor_no = empno 
START WITH empno = 1 
order by level) d 
WHERE d.empgroup = 'U' and rownum =1 

我也創建了一個小提琴，如果有幫助。 http://www.sqlfiddle.com/#!4/c8805/4

Answer 1

那麼，你的問題變得對我是個挑戰，但我沒有放棄，並得到這個只用SQL和內置函數（不應該慢慢地工作，而且相當可轉位需要）：

select distinct 
    empno, 
    empgroup, 
    username, 
    supervisor_no, 
    manager_no 
from (
    select 
      e.*, 
      decode(
     instr(
      sys_connect_by_path(empgroup, '/'), 
      'U/', 
      -1 
     ), 
     0, 
     null, 
     substr(
      sys_connect_by_path(empno, '/'), 
      instr(
       sys_connect_by_path(empno, '/'), 
       '/', 
       1, 
       length(
        substr(
         sys_connect_by_path(empgroup, '/'), 
         1, 
         instr(
          sys_connect_by_path(empgroup, '/'), 
          'U/', 
          -1 
         ) 
        ) 
       ) - length(
        replace(
         substr(
          sys_connect_by_path(empgroup, '/'), 
          1, 
          instr(
           sys_connect_by_path(empgroup, '/'), 
           'U/', 
           -1 
          ) 
         ), 
         '/' 
        ) 
       ) 
      ) + 1, 
      instr(
       sys_connect_by_path(empno, '/'), 
       '/', 
       1, 
       length(
        substr(
         sys_connect_by_path(empgroup, '/'), 
         1, 
         instr(
          sys_connect_by_path(empgroup, '/'), 
          'U/', 
          -1 
         ) 
        ) 
       ) - length(
        replace(
         substr(
          sys_connect_by_path(empgroup, '/'), 
          1, 
          instr(
           sys_connect_by_path(empgroup, '/'), 
           'U/', 
           -1 
          ) 
              ), 
               '/' 
             ) 
           ) + 1 
         ) - instr(
           sys_connect_by_path(empno, '/'), 
           '/', 
           1, 
           length(
             substr(
               sys_connect_by_path(empgroup, '/'), 
               1, 
               instr(
                 sys_connect_by_path(empgroup, '/'), 
                 'U/', 
                 -1 
               ) 
             ) 
           ) - length(
             replace(
               substr(
                 sys_connect_by_path(empgroup, '/'), 
                 1, 
                 instr(
                   sys_connect_by_path(empgroup, '/'), 
                   'U/', 
                   -1 
                 ) 
               ), 
               '/' 
             ) 
           ) 
         ) - 1 
       ) 
     ) manager_no 
    from employee e 
    connect by prior empno = supervisor_no 
) 
where manager_no is not null or supervisor_no is null 
order by empno; 

的SQL搗鼓查詢：http://www.sqlfiddle.com/#!4/c8805/27/0

UPDATE： 當我早上起牀，我意識到一切都可以做更容易和查詢變得更具可讀性，在這裏你去：

select 
    empno, 
    empgroup, 
    username, 
    supervisor_no, 
    null manager_no 
from 
    employee 
where 
    supervisor_no is null 
union all 
select 
    empno, 
    empgroup, 
    username, 
    supervisor_no, 
    substr(ep, 2, instr(ep, '/', 2)-2) manager_no 
from (
    select 
    sys_connect_by_path(empgroup, '/') gp, 
    sys_connect_by_path(empno, '/') ep, 
    e.* 
    from employee e 
    connect by prior empno = supervisor_no 
) e 
where 
    substr(gp, 1, 3) = '/U/' 
    and (length(gp) - length(replace(gp, 'U/'))) = length('U/') 
order by empno; 

它的工作原理！以及上面的查詢。SQL小提琴吧：http://www.sqlfiddle.com/#!4/c8805/54/0

享受！

Answer 2

也許創建一個遞歸函數來獲取用戶的'U'型監督員？

CREATE OR REPLACE FUNCTION GET_U_SUPERVISOR(employee_no INT) 
RETURN INT IS 
    supervisor_empno INT; 
    supervisor_group VARCHAR(20); 
BEGIN 
    SELECT empno, empgroup 
    INTO supervisor_empno, supervisor_group 
    FROM employee 
    WHERE employee.empno = (SELECT supervisor_no FROM employee WHERE empno = employee_no); 

    IF 'U' = supervisor_group 
    THEN 
     RETURN supervisor_empno; 
    ELSE 
     RETURN GET_U_SUPERVISOR(supervisor_empno); 
    END IF; 
END GET_U_SUPERVISOR; 
/

然後：

SELECT empno, empgroup, username, supervisor_no, GET_U_SUPERVISOR(empno) 
FROM employee; 

一個SQL小提琴回你：http://www.sqlfiddle.com/#!4/c7540/1/0

我不能保證在任何的表現，不過，如果它是一個大桌子。它是遞歸的，並將在每行的基礎上調用。

Answer 3

我遞歸，SQL Fiddle使用，

CREATE TABLE EMPLOYEE(NO INT, EMP_GROUP VARCHAR2(1), EUSER VARCHAR2(30), SUPERVISOR_NO INT); 

INSERT INTO EMPLOYEE VALUES(1, 'E', 'JOE SCHMO', 4); 
INSERT INTO EMPLOYEE VALUES(2, 'E', 'Mark Marin', 3); 
INSERT INTO EMPLOYEE VALUES(3, 'U', 'Reed Patter', 7); 
INSERT INTO EMPLOYEE VALUES(4, 'E', 'Martin Price ', 7); 
INSERT INTO EMPLOYEE(NO, EMP_GROUP, EUSER) VALUES(7, 'U', 'Mary Wengert'); 
WITH A(EMPLOYEE, MANAGER) AS 
(
    SELECT NO AS EMPLOYEE, SUPERVISOR_NO AS MANAGER FROM EMPLOYEE 
    UNION ALL 
    SELECT A.EMPLOYEE, E.SUPERVISOR_NO AS MANAGER 
    FROM A, EMPLOYEE E 
    WHERE A.MANAGER = E.NO 
    AND E.SUPERVISOR_NO IS NOT NULL 
) 

SELECT * FROM A 
ORDER BY 1