Find common rows

Hy, I have a query which return the following result. That is a list of rows with 2 columns. Some numbers are common in certain rows. I need to combine all common numbers in 1 row.
If I have the following rows:
ID | DUP_ID
"30007";"30008";
"30005";"30007";
"30006";"30011";
"30004";"30006";
"30001";"30006";
"30012";"30013";

my final result should be:

30007; 30008; 30005
30006; 30011; 30004; 30001
30012; 30013

How to achieve this.

thanks in advance

gul

You can do this by using two queries:
select distinct ID from table --gets the first ID's

select distinct DUP_ID from table where DUP_ID not in (select distinct ID from table)
--gets those ID's that weren't in the first batch

Or you can declare a table variable (with one column), read all of the ID's and DUP_ID's into it, and just select the distinct ID's