In a SQL request NULL and '' do not come up with the identical result

Someone knows the way to come up with the identical result for these two requests to an Oracle 8.05 table with a nullable column :

select * from table where col = '' -- this request gives back no reply and
select * from table where col IS NULL -- this request gives a reply back

Is there an option/parameter of the instance to alter in order to solve my problem ? or any other suggestion ???

Thanking you in advance for your prompt reply !

Olivier Received on Wed Jun 14 2000 - 00:00:00 CDT