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
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