select a.GroupID, stuff((select '、'+b.CountryName from [表名] b where b.GroupID=a.GroupID for xml path('')),1,1,'') 'CountryName' from [表名] a group by a.GroupID
FOR XML PATH('') 和 STUFF()例子: http://blog.sqlauthority.com/2013/04/05/sql-server-group-by-rows-and-columns-using-xml-path-efficient-concating-trick/
select a.GroupID,
stuff((select '、'+b.CountryName
from [表名] b
where b.GroupID=a.GroupID
for xml path('')),1,1,'') 'CountryName'
from [表名] a
group by a.GroupID