group_concat in mysql, oracle, mss

需求：

	tb_region
province	city		province	city
四川	成都	====》	四川	成都，绵阳，德阳
浙江	杭州	浙江	杭州，宁波
江苏	南京	江苏	南京
四川	绵阳
四川	德阳
浙江	宁波

 

mysql:

select 
province,
group_concat(distinct city order by city separator ',') as city
from
tb_region
group by province

Oracle:

select 
province,
listagg(city,',') within group (order by city) as city
from
tb_region
group by province

Sql Server:

select
r2.province,
(select
    r1.city + ','
 from tb_region r1
    where r1.province=r2.province for XML path('')) as concat_city
from tb_region r2
group by r2.province