create table tableEnd
(name varchar(6), Nos int, Descs varchar(50))

insert into tableEnd
select '某某', 1, '123,456,1254,123456' union all
select '小明', 2, '5321,123' 

create table tableRaw
(name varchar(6), Nos int, Descs varchar(50))
   
insert into tableRaw
select '某某', 1, '123' union all
select '小明', 2, '5321' union all
select '某某', 1, '555' union all
select '某某', 1, '666' union all
select '小黑', 3, '456'

select * from tableEnd

name   Nos         Descs
------ ----------- --------------------------------------------------
某某     1           123,456,1254,123456
小明     2           5321,123

select * from tableRaw

name   Nos         Descs
------ ----------- --------------------------------------------------
某某     1           123
小明     2           5321
某某     1           555
某某     1           666
小黑     3           456


;with t as
(select a.name,a.Nos,substring(a.Descs,b.number,charindex(',',a.Descs+',',b.number)-b.number) Descs 
from tableEnd a
inner join master.dbo.spt_values b
on b.[type]='P' and substring(','+a.Descs,b.number,1)=','
union
select name,Nos,Descs from tableRaw
)
select name,Nos,
stuff(
(select ','+Descs from t t2 
where t2.name=t.name and t2.Nos=t.Nos for xml path('')),
1,1,'') Descs
from t
group by name,Nos

name   Nos         Descs
------ ----------- -------------------------------
某某     1           123,123456,1254,456,555,666
小明     2           123,5321
小黑     3           456

(3 row(s) affected)

------解决方案--------------------

SQL code

create table tableEnd
(name varchar(6), Nos int, Descs varchar(50))

insert into tableEnd
select '某某', 1, '123,456,1254,123456' union all
select '小明', 2, '5321,123' 

create table tableRaw
(name varchar(6), Nos int, Descs varchar(50))
   
insert into tableRaw
select '某某', 1, '123' union all
select '小明', 2, '5321' union all
select '某某', 1, '555' union all
select '某某', 1, '666' union all
select '小黑', 3, '456'

select * from tableEnd

name   Nos         Descs
------ ----------- --------------------------------------------------
某某     1           123,456,1254,123456
小明     2           5321,123

select * from tableRaw

name   Nos         Descs
------ ----------- --------------------------------------------------
某某     1           123
小明     2           5321
某某     1           555
某某     1           666
小黑     3           456


;with t as
(select a.name,a.Nos,substring(a.Descs,b.number,charindex(',',a.Descs+',',b.number)-b.number) Descs 
from tableEnd a
inner join master.dbo.spt_values b
on b.[type]='P' and substring(','+a.Descs,b.number,1)=','
union
select name,Nos,Descs from tableRaw
)
merge tableEnd as o
using
(select name,Nos,
stuff(
(select ','+Descs from t t2 
where t2.name=t.name and t2.Nos=t.Nos for xml path('')),
1,1,'') Descs
from t group by name,Nos) as s
on o.Nos=s.Nos and o.name=s.name
when matched then
 update set o.Descs=s.Descs
when not matched then
 insert(n