Updating Multiple Records In A Table

OS:Solaris
DB:10G

I have a situation where there are multiple records for a join criteria. I am trying to find a way to update a particular column for all the records returned by the join criteria. Example :

Table A

id number

1 1000
2 2000
3 3000
4 4000

Table B

id number
1 9999
1 9999
1 9999
1 9999
1 9999
1 9999
2 8888
2 8888
3 6666
3 6666

Result after update:

Table B

id number
1 1000
1 1000
1 1000
1 1000
1 1000
1 1000
2 2000
2 2000
3 3000
3 3000

update query ? When I use a update statement with where exists it errors out because the query returns more than one row for the join condition.