oracle SYS_CONNECT_BY_PATH 函数实现将从父节点到当前行内容以“path”或者层次元素列表的形式显示出来

先创建一个树形结构的表t_test

create table T_TEST
(
	ID    NUMBER,
	PID   NUMBER,
	TITLE VARCHAR2(30)
)
tablespace TEST
pctfree 10
initrans 1
maxtrans 255
storage
(
	initial 64K
	minextents 1
	maxextents unlimited
);

insert into T_TEST (ID, PID, TITLE) values (1, 0, '一一');
insert into T_TEST (ID, PID, TITLE) values (2, 0, '二二');
insert into T_TEST (ID, PID, TITLE) values (3, 1, '一三');
insert into T_TEST (ID, PID, TITLE) values (4, 1, '一四');
insert into T_TEST (ID, PID, TITLE) values (5, 3, '一三五');
insert into T_TEST (ID, PID, TITLE) values (6, 3, '一三六');
insert into T_TEST (ID, PID, TITLE) values (7, 2, '二七');
insert into T_TEST (ID, PID, TITLE) values (8, 2, '二八');
insert into T_TEST (ID, PID, TITLE) values (9, 7, '二七九');
insert into T_TEST (ID, PID, TITLE) values (10, 7, '二七十');
commit;

 
sys_connect_by_path 函数主要作用是可以把一个父节点下的所有子节点通过某个字符进行区分，然后连接在一个列中显示 
 
--子id=父id 倒树型结构
--父id=子id   正树型结构  

先看子id=父id 倒树型结构例子：

select level ,id,pid,title,sys_connect_by_path( title , '/' ) as path
from t_test
--where level=3
start with id= 1
connect by prior id = pid order by pid; 

 
显示结果：



再看父id=子id   正树型结构 例子：

select level ,id,pid,title,sys_connect_by_path( title , '/' ) as path
from t_test
--where level=3
start with pid= 3
connect by prior pid = id order by pid; 

 结果显示：