Concat all column values in sql

Question

How to concat all column values from differenct rows returned from a sql query into one value? This is an example:

a query returns:

FOO
------
RES1

RES2
         


        

Answer 1

Quassnoi's Oracle solution is quite impressive, but I found simpler ones using SYS_CONNECT_BY_PATH() rather than the MODEL magic.

SELECT REPLACE(MAX(SYS_CONNECT_BY_PATH(foo, '/')), '/', '') conc
FROM (
    SELECT T_FOO.*, ROW_NUMBER() OVER (ORDER BY FOO) R FROM T_FOO
)
START WITH r=1
CONNECT BY PRIOR r = r-1;