What is a simple way to combine grouped values in one field? - sql

Question

I mean:
Table PHONE_CODES:
ID CODE_NAME PHONE_CODE
1 USA 8101
2 USA 8102
3 PERU 8103
4 PERU_MOB 81031
5 PERU_MOB 81032
And I want via select to get something like this:
CODE_NAME ZONE_CODES
USA 8101; 8102;
PERU 8103
PERU_MOB 81031; 81032;
I could get it via the function below, but perhaps there is a better way:
select distinct(CODE_NAME) as CODE_NAME, get_code_names_by_ZONE(CODE_NAME) as ZONE_CODES from PHONE_CODES;
Function:
create or replace function get_code_names_by_ZONE
(
ZONE_CODE_NAME in varchar2
)
return varchar2
as
codes_list varchar2(4000);
cursor cur_codes_list is
select p.PHONE_CODE
from PHONE_CODES p
where p.CODE_NAME = ZONE_CODE_NAME;
begin
for codes_list_rec in cur_codes_list
LOOP
-- dbms_output.put_line('PHONE_CODE:[' || codes_list_rec.PHONE_CODE || ']');
codes_list := codes_list || codes_list_rec.PHONE_CODE || '; ';
end loop;
return codes_list;
EXCEPTION
when NO_DATA_FOUND then
return 'notfound';
WHEN others then
dbms_output.put_line('Error code:' || SQLCODE || ' msg:' || SQLERRM);
return null;
end get_code_names_by_ZONE;
/

Answer 1

Tim Hall has an excellent discussion on the various string aggregation techniques that are available in Oracle.

Answer 2

A function would be my preferred method of achieving what you want.

Answer 3

If you're on 11g, take a look at the new PIVOT extension to SQL - the best documentation looks to be in the Data Warehousing Guide section. I believe however that the target of the "... for in ..." clause cannot be a subquery and has to be a hard-coded list of values.

Answer 4

Good link Justin. Tim hall is awesome. I followed his advice and here it is:
1 SELECT CODE_NAME,
2 LTRIM(MAX(SYS_CONNECT_BY_PATH(PHONE_CODES,';'))
3 KEEP (DENSE_RANK LAST ORDER BY curr),';') AS PHONE_CODES
4 FROM (SELECT CODE_NAME,
5 PHONE_CODES,
6 ROW_NUMBER() OVER (PARTITION BY CODE_NAME ORDER BY PHONE_CODES) AS curr,
7 ROW_NUMBER() OVER (PARTITION BY CODE_NAME ORDER BY PHONE_CODES) -1 AS prev
8 FROM a)
9 GROUP BY CODE_NAME
10 CONNECT BY prev = PRIOR curr AND CODE_NAME = PRIOR CODE_NAME
11* START WITH curr = 1
SQL> /
CODE_NAME PHONE_CODES
---------- --------------------------------------------------
PERU 8103
PERU_MOB 81031;81032
USA 8101;8102
dbBradley - I don't think the Pivot extension works here. The Pivot extension requires the use of an aggregate (sum, count, ...).