[GENERAL] plpgsql, I have a solution, want to see if there is a cleaner/better one. Taking vertical list and comma separating it onto a row

[Henry Drexler]

I am thinking there is a better/simpler way, though this is what I have
working:

(postgres 9.1)


I would like to have the list of colors for each type of clothing to be
comma seperated in the end result.

like this:

type        organized_by_type
pants     red, blue, orange
shirt       black, gray


though with my current solution it looks like this:

type        organized_by_type
pants     , red, , blue, ,orange,
shirt       , black, ,gray,


I know I can add more logic in to get rid of the leading and ending commas,
etc, but it seem like there would be a cleaner more elegant solution.






table
-----------------

-- Table: clothes

-- DROP TABLE clothes;

CREATE TABLE clothes
(
  type character varying,
  color character varying
)
WITH (
  OIDS=FALSE
);
ALTER TABLE clothes
  OWNER TO postgres;



insert into clothes values('shirt','red');
insert into clothes values('shirt','blue');
insert into clothes values('shirt','orange');
insert into clothes values('pants','black');
insert into clothes values('pants','gray');




create or replace function organized_by_type(input text) returns text
language plpgsql as $$
DECLARE
item alias for $1;
t text;
groups text;
r integer;
BEGIN
groups = '';
select into r count(color) from clothes where type = item;

for i in 1..r loop
select into t
color
from
clothes
where
type = item
limit 1 offset i-1;

groups = groups || ', ' || t || ', ';
RAISE NOTICE 'value groups: %    value t: %',groups,t;
end loop;
return groups;
END
$$



Query with result
------------------------------

select
type,
organized_by_type(type)
from
clothes
group by type

type        organized_by_type
pants     red, blue, orange
shirt       black, gray