--A表(记录表)
DECLARE @A TABLE(id INT,Tag VARCHAR(10))
--ID Tag
-----------
INSERT INTO @A
SELECT 1, '1,2,3' UNION ALL
SELECT 2, '1,3' UNION ALL
SELECT 3, '2,3'

DECLARE @B TABLE(id INT,描述 VARCHAR(10))
-------------
INSERT INTO @B
SELECT 1, '拉面' UNION ALL
SELECT 2, '方便面' UNION ALL
SELECT 3, '牛肉面' 

SELECT a.id,
a.Tag,
TagName=STUFF((SELECT ','+描述 FROM @B WHERE CHARINDEX(','+CAST(id AS VARCHAR(4))+',',','+a.Tag+',' )>0 FOR XML PATH('')),1,1,'')
FROM @A  a
GROUP BY a.id,Tag
/*
id          Tag        TagName
----------- ---------- -------------------------
1           1,2,3      拉面,方便面,牛肉面
2           1,3        拉面,牛肉面
3           2,3        方便面,牛肉面

(3 行受影响)
*/

------解决方案--------------------
SQL code

--> 测试数据：[A表]
if object_id('[A表]') is not null 
drop table [A表]
create table [A表](
[ID] int,
[Tag] varchar(5)
)
go
insert [A表]
select 1,'1,2,3' union all
select 2,'1,3' union all
select 3,'2,3'
go
--> 测试数据：[B表]
if object_id('[B表]') is not null 
drop table [B表]
create table [B表](
[ID] int,
[描述] varchar(6)
)
go
insert [B表]
select 1,'拉面' union all
select 2,'方便面' union all
select 3,'牛肉面'
go
;with t
as(
select a.*,b.描述
from [A表] a,[B表] b 
where CHARINDEX(LTRIM(b.[ID]),a.Tag)>0
)
SELECT *FROM (SELECT DISTINCT Id,Tag FROM t)A
OUTER APPLY(
    SELECT [描述]= STUFF(REPLACE(REPLACE(
            (   SELECT [描述] FROM t N
                WHERE id = A.id and Tag=a.Tag
                FOR XML AUTO
             ), '<b 描述="', ','), '"/>', ''), 1, 1, '')
)N
/*
Id    Tag    描述
---------------------------------
1    1,2,3    拉面,方便面,牛肉面
2    1,3    拉面,牛肉面
3    2,3    方便面,牛肉面
*/