Question

I have a simple query:

select * from countries 

with the following results:

country_name ------------ Albania Andorra Antigua ..... 

I would like to return the results in one row, so like this:

Albania, Andorra, Antigua, ... 

Of course, I can write a PL/SQL function to do the job (I already did in Oracle 10g), but is there a nicer, preferably non-Oracle-specific solution (or may be a built-in function) for this task?

I would generally use it to avoid multiple rows in a sub-query, so if a person has more then one citizenship, I do not want her/him to be a duplicate in the list.

My question is based on the similar question on SQL server 2005.

UPDATE: My function looks like this:

CREATE OR REPLACE FUNCTION APPEND_FIELD (sqlstr in varchar2, sep in varchar2 ) return varchar2 is ret varchar2(4000) := ''; TYPE cur_typ IS REF CURSOR; rec cur_typ; field varchar2(4000); begin      OPEN rec FOR sqlstr;      LOOP          FETCH rec INTO field;          EXIT WHEN rec%NOTFOUND;          ret := ret || field || sep;      END LOOP;      if length(ret) = 0 then           RETURN '';      else           RETURN substr(ret,1,length(ret)-length(sep));      end if; end; 

Answer 1

Here is a simple way without stragg or creating a function.

create table countries ( country_name varchar2 (100));  insert into countries values ('Albania');  insert into countries values ('Andorra');  insert into countries values ('Antigua');   SELECT SUBSTR (SYS_CONNECT_BY_PATH (country_name , ','), 2) csv       FROM (SELECT country_name , ROW_NUMBER () OVER (ORDER BY country_name ) rn,                    COUNT (*) OVER () cnt               FROM countries)      WHERE rn = cnt START WITH rn = 1 CONNECT BY rn = PRIOR rn + 1;  CSV                                                                              -------------------------- Albania,Andorra,Antigua                                                           1 row selected. 

As others have mentioned, if you are on 11g R2 or greater, you can now use listagg which is much simpler.

select listagg(country_name,', ') within group(order by country_name) csv   from countries;  CSV                                                                              -------------------------- Albania, Andorra, Antigua  1 row selected.