Dünyada 10 çeşit insan vardır, binary bilenler ve bilmeyenler.

yurt interneti kesik, xmldb, kayıt, memleket derken blog unutuldu :(

Ve evet efenim:

PL/SQL supports shut-circuits, but optimizer may change your logic :) . Anyway, this is a good way to process optional join parts:

select *
from hede h
where (h.n_hard_join = '13' OR some_var = '13')

when evaluating query if some_var is 13 then h.n_hard_join = '13' wont be evaluated.

sources:
http://forums.oracle.com/forums/thread.jspa?messageID=51765&#51765
KaPlan!!!