通過指定根和葉節點的oracle分層查詢

Question

我有一個oracle表，其中包含以下字段MgrID，EmpID，Name。

層次結構實際上始於CEO級別，但我希望將CIO的EmpID指定爲特定員工的根和EmpID並獲取該員工的層次結構。我如何在Oracle中構建該查詢？

Answer 1

在ORCALE可以使用選擇與開始與和

select * from your_table 
start with EmpID = yuor_value 
connect by prior your_child = your_parent; 

Answer 2

甲骨文設置連接：

CREATE TABLE Table_name (
    EmpID INT PRIMARY KEY, 
    MgrID INT REFERENCES Table_name (EmpID), 
    Name VARCHAR2(10), 
    Role VARCHAR2(10) 
); 

INSERT INTO table_name 
SELECT 1, NULL, 'Amy',  'CEO'  FROM DUAL UNION ALL 
SELECT 2, 1, 'Bob',  'Director' FROM DUAL UNION ALL 
SELECT 3, 1, 'Carol', 'Director' FROM DUAL UNION ALL 
SELECT 4, 2, 'Deb',  'CIO'  FROM DUAL; 

查詢：

SELECT * 
FROM table_name 
START WITH role = 'CIO' 
CONNECT BY PRIOR MgrID = EmpID; 

輸出：

 EMPID  MGRID NAME  ROLE  
---------- ---------- ---------- ---------- 
     4   2 Deb  CIO   
     2   1 Bob  Director 
     1   Amy  CEO