isnull() or is it?

A while back there was some discussion about NULL.  Right now I'm trying
to do something that 'Practical SQL' seems to think is normal yet brings up
the questions from earlier conversations.  I'm querying two tables where
if the second table (specialprice) has nothing that matches sku, I don't 
care.  IIRC this is how I do it in Sybase (don't have the actual calls in
front of me so I don't know if I'm mistaken).  The following select call:

select
products.image,products.sizes,products.colors,products.weight,products.categor
y,products.accessories,products.saleprice,products.ourcost,products.descriptio
n,isnull(specialprice.specialprice,0.0) from products,specialprice where
products.sku = '28434' and (specialprice.sku = '28434' or specialprice is
null);

results in this:

ERROR:  No such function 'isnull' with the specified attributes

I thought that isnull() was something that existed in PostgreSQL 6.4, am
I wrong or is it implemented differently than Sybase?  Or am I not making
sense (it should be easy to explain if I'm not)?

Vince.
-- 
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Vince Vielhaber -- KA8CSH   email: vev@michvhf.com   flame-mail: /dev/null      # include <std/disclaimers.h>
       TEAM-OS2  Online Searchable Campground Listings    http://www.camping-usa.com      "There is no outfit less
entitledto lecture me about bloat              than the federal government"  -- Tony Snow
 
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