Oracle用Start with...Connect By子句递归查询

小破孩子

Start with...Connect By子句递归查询一般用于一个表维护树形结构的应用。
创建示例表：
CREATE TABLE TBL_TEST
(
  ID    NUMBER,
  NAME  VARCHAR2(100 BYTE),
  PID   NUMBER                                  DEFAULT 0
);

插入测试数据：
INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('1','10','0');
INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('2','11','1');
INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('3','20','0');
INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('4','12','1');
INSERT INTO TBL_TEST(ID,NAME,PID) VALUES('5','121','2');

从Root往树末梢递归
select * from TBL_TEST
start with id=1
connect by prior id = pid

从末梢往树ROOT递归
select * from TBL_TEST
start with id=5
connect by prior pid = id
select * from test_tt;
      
1 10 0
2 11 1
3 20 0
4 12 1
5 121 2
select * from test_tt
start with id=1
connect by prior id = pid
1 10 0
2 11 1
5 121 2
4 12 1
select * from TBL_TEST
start with id=5
connect by prior pid = id

5 121 2
2 11 1
1 10 0

select * from test_tt
start with id=5
connect by prior id = pid
5 121 2