Oracle中自带的递归查询(connect by)

做个测试

 CREATE TABLE a

(

ID    NUMBER,

NAME VARCHAR2(100 BYTE),

PID   NUMBER                                  DEFAULT 0

);

插入测试数据：

INSERT INTO a(ID,NAME,PID) VALUES('1','10','0');

INSERT INTO a(ID,NAME,PID) VALUES('2','11','1');

INSERT INTO a(ID,NAME,PID) VALUES('3','20','0');

INSERT INTO a(ID,NAME,PID) VALUES('4','12','1');

INSERT INTO a(ID,NAME,PID) VALUES('5','121','2');

 从Root往树末梢递归 

select * from a;

id      name      pid

1 10 0

2 11 1

3 20 0

4 12 1

5 121 2


select * from a
start with id=1
connect by prior id = pid;
id      name      pid
1 10 0
2 11 1
5 121 2
4 12 1


 从末梢往树ROOT递归
select * from a
start with id=5
connect by prior pid = id
id      name     pid
1 10 0
2 11 1
5 121 2
4 12 1