conditional check in oracle

[rahulvasanth]

HI

I have the following query in a procedure

select a.S_No,
a.transaction,
a.r_no,
b.credit_card_No,
b.credit_card_amount,
c.check_number,
c.check_amount,
from rpt a,
credit_card b,
check b,
where a.r_no = b.r_no(+)
and a.r_no = c.r_no(+)

I m passing a value to the procedure ("check" or "card")

if the value is blank then I have to consider all the tables, but if I pass "Check" then I have to consider only rpt and check table. And if I pass "Card" then I have to consider only rpt and credit_card tables.

Can some one guide me on how I can do the coditional check

thanking in advance

[pclement]

You can use the Case expression:

http://www.oracle-base.com/articles/9i/Case9i.php