How to convert a select query into a CSV

Source:

http://stackoverflow.com/questions/468990/how-can-i-combine-multiple-rows-into-a-comma-delimited-list-in-oracle

Goal:

 create table countries ( country_name varchar2 (100));  
 insert into countries values ('Albania');  
 insert into countries values ('Andorra');  
 insert into countries values ('Antigua');  


 SELECT * from countries;  
 COUNTRY_NAME       
 ----------------------  
 Albania         
 Andorra         
 Antigua    
 Goal:   


 select * from ();   
 CSV  
 ----------------------  
 Albania, Andorra, Antigua  

Solution: 

 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.