Using function in where clause

Question

I have created a function as follows
create or replace FUNCTION get_codes RETURN varchar2 IS
scodes varchar2(50) := 'A1,A2';
BEGIN
scodes := '('''||REPLACE(scodes,',',''',''')||''')';
return scodes;
END;
this function returns ('A1','A2')
now i want to use this in where clause, both below statements fetches no rows
select * from tablea where code in (select get_codes from dual);
select * from tablea where code in get_codes;
but the following will fetch rows
select * from tablea where code in ('A1','A2')
how to use function in where clause
Thanks

Answer 1

Hi,
The code that works:
where code in ('A1','A2')is testing whther code is either of two 2-character strings, A1 or A2.
The ones that don't work, such as:
where code in get_codes;are comparing code to one 9-character string: 'A1','A2', where characters 1, 4, 6 and 9 are single-quotes. (The function can only return one value.)
You can use dynamic SQL to embed that 9-character string in part of your query, where it will be interpreted as two 2-character strrings.
[Oracle Base|http://www.oracle-base.com/articles/misc/DynamicInLists.php] and AskTom have good pages on the subject of dynamic IN-lists.
Of you can use INSTR or LIKE:
where INSTR ( get_codes
            , '''' || code || ''''
            ) > 0