I need to denormalize data in sql query, please help!

Question

With the query
select ref, start_time, end_time, person
from appointments
I get, eg:
REF START_TIME END_TIME PERSON
1234 10:00 11:00 USER1
1234 10:00 11:00 USER2
The users want to see it like this:
REF START_TIME END_TIME PERSON
1234 10:00 11:00 USER1, USER2
How do I do this just in sql?
cheers
Tracey.

Answer 1

Apologies, my mistake, I forgot to connect by the ref as well...
(Note: you can ignore the CAST to VARCHAR2(40) as that just helped me get the formatted output.)
SQL> ed
Wrote file afiedt.buf
  1  with t as (select 1234 as ref, '10:00' as start_time, '11:00' as end_time, 'USER1' as person from dual union all
  2             select 1234, '10:00', '11:00', 'USER2' from dual union all
  3             select 345, '11:00', '12:00', 'USER3' from dual)
  4  -- END OF TEST DATA
  5  select ref, start_time, end_time, CAST(MAX(LTRIM(SYS_CONNECT_BY_PATH(person,', '),', ')) AS VARCHAR2(40)) as users
  6  from (select ref, start_time, end_time, person
  7              ,row_number() over (partition by ref, start_time, end_time order by person) rn
  8        from t) t
  9  CONNECT BY rn = PRIOR rn+1 AND ref = PRIOR ref
10  START WITH rn = 1
11* GROUP BY ref, start_time, end_time
SQL> /
       REF START END_T USERS
      1234 10:00 11:00 USER1, USER2
       345 11:00 12:00 USER3
SQL>