Thanks for all the suggestions guys. I've managed to reduce the overhead of doing a subselect by using a temp table and doing a join so the urgency is...

arun.sas (4/22/2009)

try this,

SELECT a.blah, b.de, case when isnull(b.blah,0)> 0 then 1 else 0 end /*CASE b.blah WHEN NULL THEN 0 ELSE 1 END*/ as blah,

FROM tableA a

LEFT OUTER JOIN tableB...