SQL select a concatination of entries from another table

Question

I am trying to select a few columns from one table and then add another column that is a concatination or names from another table that referances it as below. Is this possible to do in one select statement?
table x1
ID NAME
1 Bob
1 Tom
2 Bill
table x2
ID NAMES
1 Bob, Tom
2 Bill
3

Answer 1

You mean string aggregation?
If yes, then it is possible like this, if you are on 10g.
SQL> create table x1 (id,name)
  2  as
  3  select 1, 'Bob' from dual union all
  4  select 1, 'Tom' from dual union all
  5  select 2, 'Bill' from dual
  6  /
Tabel is aangemaakt.
SQL> select id
  2       , rtrim(n,', ') names
  3    from ( select id
  4                , n
  5                , rn
  6             from x1
  7            model
  8                  partition by (id)
  9                  dimension by (row_number() over (partition by id order by null) rn)
10                  measures (cast(name as varchar2(20)) n)
11                  rules
12                  ( n[any] order by rn desc = n[cv()] || ', ' || n[cv()+1]
13                  )
14         )
15   where rn = 1
16  /
        ID NAMES
         1 Bob, Tom
         2 Bill
2 rijen zijn geselecteerd.There are several other (slower) techniques possible as well. You can find them by using the search function on this forum.
Regards,
Rob.