Nested DECODE?

[Quoted] Can anyone tell me if it is possible (and if so, how) to nest DECODE clauses within a select statement?

For example, I want to select a from tbla, except if a is null, then I want b from tblb, except if b is null then I want c from tblc.

This works:
select decode(a2,'', 'nu',a2) from asl where a1 = 'K1';

but if I try to replace 'nu' with a subselect-decode, it doesn't as given:

select decode(w2,'',

          (select decode(a2,'','nu', a2) from asl where a1 = 'K1' )

, w2) from wms where w1 = 'K1';

Oracle returns ORA-00936: missing expression.

Any suggestions would be helpful
-steven
sfware_at_idirect.com Received on Fri Feb 21 1997 - 00:00:00 CET