/*Oracle树形结构查询*/

关键词start with…connect by

create table  diqu(id int ,address varchar2(10)  not null,parent_id int);insert into diqu(id,address,parent_id) values(100,'中国','0');insert into diqu(id,address,parent_id) values(110,'湖南','100');insert into diqu(id,address,parent_id) values(130,'四川','100');insert into diqu(id,address,parent_id) values(120,'湖北','100');insert into diqu(id,address,parent_id) values(111,'长沙','110');insert into diqu(id,address,parent_id) values(112,'株洲','110');insert into diqu(id,address,parent_id) values(113,'衡阳','110');insert into diqu(id,address,parent_id) values(121,'武汉','120');insert into diqu(id,address,parent_id) values(122,'黄冈','120');insert into diqu(id,address,parent_id) values(131,'成都','130');insert into diqu(id,address,parent_id) values(132,'乐山','130');select * from diqu--prior在前   查爸爸select *from diqu start with id=130connect by diqu.id=prior parent_id；--prior在后 查儿子select *from diqu start with id=130connect by prior diqu.id= parent_id；