How return a list in PL/SQL - sql

Question

I'm trying to return a list of char in a function PL/SQL with Oracle 11, but without succes.
I've got a few difficulties for understand their running...
For example, i have this code created for test:
create type test is table of varchar(500);
/
CREATE OR REPLACE FUNCTION test2 (id INT)
RETURN test
is
tt_t test;
BEGIN
SELECT descriptifSpecifique INTO tt_t(1)
FROM DECOMPOSE
where idRecette=id
AND idEtape=2;
SELECT descriptifSpecifique INTO tt_t(2)
FROM DECOMPOSE
where idRecette=id
AND idEtape=3;
RETURN tt_t;
END;
/
show errors function test;
The fonction is created without compilation's problem, but at the execution, I have this message: ORA-06531: Reference to uninitialized collection.
Also, how can I return a type (with a varchar and a int generated by a select for example) IN PL/SQL. Because when I try to make a declaration of type with RECORD, and RETURN this type, I have compilation's problem because type is not declarated...
Thank you

Answer 1

You are basically doing it correctly. But you need to EXTEND your collection before you put new elements into it.
Personally, I prefer to BULK COLLECT into the collection to avoid having to EXTEND and manage the entries at each index. Like this (code untested):
CREATE OR REPLACE FUNCTION test2 (id INT)
RETURN test
is
tt_t test;
BEGIN
SELECT descriptifSpecifique
BULK COLLECT INTO tt_t
FROM DECOMPOSE
where idRecette=id
AND idEtape IN (2,3)
ORDER BY idEtape;
RETURN tt_t;
END;
/
To return a TYPE having multiple columns, you need to create two types: an OBJECT type and a TABLE OF that object type.
Like so,
CREATE TYPE test_rec IS OBJECT ( a_varchar VARCHAR2(500), a_number NUMBER);
CREATE TYPE test_tbl IS TABLE OF test_rec;
Then, you can modify your function accordingly:
CREATE OR REPLACE FUNCTION test2 (id INT)
RETURN test_tbl
is
tt_t test_tbl;
BEGIN
SELECT test_rec(idEtape, descriptifSpecifique)
BULK COLLECT INTO tt_t
FROM DECOMPOSE
where idRecette=id
AND idEtape IN (2,3)
ORDER BY idEtape;
RETURN tt_t;
END;
/