I am not sure, but you could try this

select a.col1, a.col2,a.col3,b.col4
from tabA a, tabB b
where a.col1+a.col2+a.col3 = b.col1+b.col2+b.col3(+)




i mean, combine the 3 columns and use the outer join

Let me know the result

badrinath