Update Statement With COALESCE

Hi All,
It seems to me I am missing some thing while using update with COALESCE...Please help me...


I have two tables called @table1 and @table2

@table1
------------------------
ID | filelis
---------------------
1 |

2 |
3 |
------------------------

@table2
------------------------
ID | file
---------------------
1 | a.txt

1 | b.txt
1 | c.txt
2 | a.exe

2 | b.exe
2 | c.exe
3 | a.alto

3 | b.alto
3 | c.alto
------------------------

I need to get file name from @table2 and update in @table1 with coma separated for each ID

the updated @table1 should be below
------------------------
ID | filelis
---------------------
1 | a.txt, b.txt, c.txt

2 | a.exe, b.exe, c.exe
3 | a.alto, b.alto, c.alto
------------------------

HERE IS THE SCRIPT for above two tables
==================================

declare @table1 table

(

ID INT,

files varchar(MAX)

)

INSERT INTO @table1 (ID,files) values(1,'')

INSERT INTO @table1 (ID,files) values(2,'')

INSERT INTO @table1 (ID,files) values(3,'')



declare @table2 table

(

ID INT,

[file] varchar(255)

)

INSERT INTO @table2 (ID,[file]) values(1,'a.txt')

INSERT INTO @table2 (ID,[file]) values(1,'b.txt')

INSERT INTO @table2 (ID,[file]) values(1,'c.txt')

INSERT INTO @table2 (ID,[file]) values(2,'a.exe')

INSERT INTO @table2 (ID,[file]) values(2,'b.exe')

INSERT INTO @table2 (ID,[file]) values(2,'c.exe')

INSERT INTO @table2 (ID,[file]) values(3,'a.alto')

INSERT INTO @table2 (ID,[file]) values(3,'b.alto')

INSERT INTO @table2 (ID,[file]) values(3,'c.alto')

select * from @table1

select * from @table2
=================================================


I have tried like this but no luck..Thanks in Advance.


update @table1

set files = COALESCE(t2.[file] + ',','') + t2.[file]

from @table1 t1,@table2 t2 where t1.ID = t2.ID