方法一：

create table #Tmp (nu int, val varchar(100))

insert into #Tmp values(1, 'a')

insert into #Tmp values(2, 'b')

insert into #Tmp values(2, 'c')

insert into #Tmp values(3, 'd')

insert into #Tmp values(3, 'e')

insert into #Tmp values(3, 'f')

select * from #Tmp

;with Orign as

(

select ROW_NUMBER() over(partition by nu order by nu) as rn, nu, val from #Tmp

),

recur as

(

select * from Orign where rn = 1

union all

select a.rn, , cast(b.val + ',' + a.val as varchar(100))as val

from Orign a

inner join recur b

on = and a.rn = b.rn+1

)

select nu, val

from recur a

where a.rn = (select max(rn)from recur b where = )

order by nu

drop table #Tmp

方法二：

create table #Tmp (nu int, val varchar(100))

insert into #Tmp values(1, 'a')

insert into #Tmp values(2, 'b')

insert into #Tmp values(2, 'c')

insert into #Tmp values(3, 'd')

insert into #Tmp values(3, 'e')

insert into #Tmp values(3, 'f')

insert into #Tmp values(4, 'g')

insert into #Tmp values(4, 'h')

insert into #Tmp values(4, 'i')

select * from #Tmp

select ','+val as [text()] from #Tmp t2 for xml path ('')

select nu, stuff( (select ','+val as [text()] from #Tmp t2 where = for xml path ('')),1,1,'')

from #Tmp t1

group by nu

drop table #Tmp

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