oracle關於樹形節點處理

create table automobiles(
part_id number(5) constraint pk_auto_part_id primary key,
parent_id number(5) constraint fk_auto_ppid_ references automobiles(part_id),
part_cname varchar2(30) not null,
part_ename varchar2(30) not null,
mp_cost number(9,2),
desribe varchar2(20)
);
--插入數據
insert into automobiles values( 1,1,'汽車','mobile',84321.99,'Assembly');
insert into automobiles values( 2,1,'車身','bodywork',19892.99,'Manufacture');
insert into automobiles values( 3,1,'發送機','engine',42128,'Purchase');
insert into automobiles values( 4,1,'附件','attached',15212,'Assembly');
insert into automobiles values( 5,2,'保險槓','bumper',4812.95,'Purchase');
insert into automobiles values( 6,2,'底盤','chassis',12795.11,'Manufacture');
insert into automobiles values( 7,2,'行李箱','Boot',812.11,'Manufacture');
insert into automobiles values( 8,6,'車輪','Wheel',2062.2,'Manufacture');
insert into automobiles values( 9,6,'擋泥板','Mudguard',990,'Manufacture');
insert into automobiles values( 10,8,'輪胎','Tyre',300,'Purchase');
insert into automobiles values( 11,3,'發送機盤','Bonnet',3212,'Manufacture');
insert into automobiles values( 12,3,'活塞','Piston',1112.2,'Manufacture');
insert into automobiles values( 13,3,'汽化器','Carburetter',712.29,'Manufacture');
insert into automobiles values( 14,4,'變速器','Gearbox',5712.25,'Manufacture');
insert into automobiles values( 15,4,'儀表板','Dashboard',538.92,'Manufacture');
insert into automobiles values( 16,14,'制動器','Carburetter',712.29,'Manufacture');
insert into automobiles values( 17,14,'變速桿','Gearshift',2001,'Manufacture');
insert into automobiles values( 18,17,'傳動軸','Shaft',1101,'Manufacture');
insert into automobiles values( 19,15,'里程錶','Milometer',350.28,'Purchase');
--分層顯示當一級目錄的父節點不爲空時容易出現loop循環找parent_id就找不到了
--解決辦法加上nocycle就可以了，或者把你的數據1,1--〉改爲1,null
select level,part_id,parent_id,part_cname,part_ename,mp_cost,desribe
from automobiles
start with part_id=1
connect by nocycle prior part_id=parent_id
order by level;
--縮進顯示節點
select level,
lpad(' ',2*level-1)||part_cname||' '||part_ename as partName
from automobiles
start with part_id=1
connect by nocycle prior part_id=parent_id
order by level;