if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([Name] varchar(1),[Age] int,[NO] int,[Remark] varchar(3))
insert [tb]
select 'A',11,11,'ABC' union all
select 'A',11,11,'CCC' union all
select 'A',11,11,'AAA' union all
select 'B',11,11,'CCC' union all
select 'B',11,11,'DDD' union all
select 'A',11,11,NULL
go

select name,age,no,
  remark=stuff((select ','+remark from tb where remark is not null and name=t.name and age=t.age and no=t.no for xml path('')),1,1,'')
from tb t
where remark is not null
group by name,age,no
UNION ALL
SELECT * FROM TB WHERE REMARK IS NULL

/**
name age         no          remark
---- ----------- ----------- -----------------------
A    11          11          ABC,CCC,AAA
B    11          11          CCC,DDD
A    11          11          NULL

(3 行受影响)
**/