--1 建表

create table city_table

(

city_name varchar2(100)

,District varchar2(100)

);

--2 插入数据

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘东城区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘西城区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘崇文区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘宣武区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘朝阳区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘海淀区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘丰台区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘石景山区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘门头沟区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘房山区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘通州区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘顺义区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘昌平区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘大兴区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘怀柔区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘平谷区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘密云县‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘北京‘, ‘延庆县‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘河东区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘河西区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘南开区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘河北区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘红桥区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘塘沽区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘汉沽区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘大港区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘东丽区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘西青区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘北辰区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘津南区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘武清区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘宝坻区‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘静海县‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘宁河县‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘蓟县‘);

insert into CITY_TABLE (CITY_NAME, DISTRICT)values (‘天津‘, ‘和平区‘);

commit;

--进击吧

select city_name,wm_concat(District||chr(10))

from city_table

group by city_name;

--结果发现，里面的子信息会按照一行一行的方式进行排列(chr(13),chr(10))

chr(9)的作用是空格

原文：http://www.cnblogs.com/88893636-xuyang/p/6945469.html