SQL Query to concatenate column values from multiple rows in Oracle

Question

Would it be possible to construct SQL to concatenate column values from multiple rows?

The following is an example:

Table A

PID
A
B
C

Answer 1

Before you run a select query, run this:

SET SERVEROUT ON SIZE 6000

SELECT XMLAGG(XMLELEMENT(E,SUPLR_SUPLR_ID||',')).EXTRACT('//text()') "SUPPLIER" 
FROM SUPPLIERS;