with temp as(
select 'China' nation,'Guangzhou' city from dual union all
select 'China' nation,'Shanghai' city from dual union all
select 'China' nation,'Beijing' city from dual union all
select 'USA' nation,'New York' city from dual union all
select 'USA' nation,'Bostom' city from dual union all
select 'Japan' nation,'Tokyo' city from dual
)
select nation,listagg(city,',') within GROUP (order by city)
from temp
group by nation ;
LISTAGG(XXX,XXX) WITHIN GROUP( ORDER BY XXX)
@H_502_1@@H_502_1@同样是聚合函数，还有一个高级用法 over(partition by XXX)，在不使用Group by语句时候，也可以使用LISTAGG函数，为了进一步演示，我们对原先的表稍加改造：
with temp as(
select 500 population,'China' nation,'Guangzhou' city from dual union all
select 1500 population,'Shanghai' city from dual union all
select 500 population,'Beijing' city from dual union all
select 1000 population,'USA' nation,'New York' city from dual union all
select 500 population,'Bostom' city from dual union all
select 500 population,'Japan' nation,'Tokyo' city from dual
)
select population,
nation,
city,
listagg(city,') within GROUP (order by city) over (partition by nation) rank
from temp
PS：在listagg(city,'/')这里我们可以使用我们想要的分隔符。
