Oracle递归查询

CREATE TABLE DISTRICT
(
  ID         NUMBER(10)                  NOT NULL,
  PARENT_ID  NUMBER(10),
  NAME       VARCHAR2(255 BYTE)          NOT NULL
);

ALTER TABLE DISTRICT ADD (
  CONSTRAINT DISTRICT_PK
 PRIMARY KEY
 (ID));

ALTER TABLE DISTRICT ADD (
  CONSTRAINT DISTRICT_R01 
 FOREIGN KEY (PARENT_ID) 
 REFERENCES DISTRICT (ID));

insert into DISTRICT (id, parent_id, name)
values (1, null, '四川省');
insert into DISTRICT (id, parent_id, name)
values (2, 1, '巴中市');
insert into DISTRICT (id, parent_id, name)
values (3, 1, '达州市');
insert into DISTRICT (id, parent_id, name)
values (4, 2, '巴州区');
insert into DISTRICT (id, parent_id, name)
values (5, 2, '通江县');
insert into DISTRICT (id, parent_id, name)
values (6, 2, '平昌县');
insert into DISTRICT (id, parent_id, name)
values (7, 3, '通川区');
insert into DISTRICT (id, parent_id, name)
values (8, 3, '宣汉县');
insert into DISTRICT (id, parent_id, name)
values (9, 8, '塔河乡');
insert into DISTRICT (id, parent_id, name)
values (10, 8, '三河乡');
insert into DISTRICT (id, parent_id, name)
values (11, 8, '胡家镇');
insert into DISTRICT (id, parent_id, name)
values (12, 8, '南坝镇');
insert into DISTRICT (id, parent_id, name)
values (13, 6, '大寨乡');
insert into DISTRICT (id, parent_id, name)
values (14, 6, '响滩镇');
insert into DISTRICT (id, parent_id, name)
values (15, 6, '龙岗镇');
insert into DISTRICT (id, parent_id, name)
values (16, 6, '白衣镇');
commit;

SELECT *
FROM district
START WITH NAME ='巴中市'
CONNECT BY PRIOR ID=parent_id

SELECT *
FROM district
START WITH NAME ='平昌县'
CONNECT BY PRIOR parent_id=ID

SELECT d.*,
connect_by_root(d.id),
connect_by_root(NAME)
FROM district d
WHERE NAME='平昌县'
START WITH d.parent_id=1    --d.parent_id is null 结果为四川省
CONNECT BY PRIOR d.ID=d.parent_id

SELECT ID,parent_id,NAME,
sys_connect_by_path(NAME,'->') namepath,
LEVEL
FROM district 
START WITH NAME='巴中市'
CONNECT BY PRIOR ID=parent_id

WITH t (ID ,parent_id,NAME) --要有列名
AS(
SELECT ID ,parent_id,NAME FROM district WHERE NAME='巴中市'
UNION ALL
SELECT d.ID ,d.parent_id,d.NAME FROM t,district d --要指定表和列表，
WHERE t.id=d.parent_id
)
SELECT * FROM t;

WITH t (ID ,parent_id,NAME) --要有表
AS(
SELECT ID ,parent_id,NAME FROM district WHERE NAME='通江县'
UNION ALL
SELECT d.ID ,d.parent_id,d.NAME FROM t,district d --要指定表和列表，
WHERE t.parent_id=d.id
)
SELECT * FROM t;