convert null date to sysdate

is it possible to convert null value date coloumn into sysdate?

i have 1 record in table whose from date is 1-oct-2010 and to_date is null. i want to return that record by using the following query by only comparing with null

select from A Where .....

AND (('1-NOV-2010' between OM_MERCH_CUST.MC_FM_DT AND OM_MERCH_CUST.MC_TO_DT)

OR('30-NOV-2010' between OM_MERCH_CUST.MC_FM_DT AND OM_MERCH_CUST.MC_TO_DT));