Problem with decode!!!

Question

Hi guys,
I have a problem with "decode"!
How can I tell the decode expression
that if a rowset don't exists --> then doing something.
I've tried that with "NULL" but that don't works.
here my code:
I wanted that if tx.text doesn't exists then
it returns fs.anlageschwerpunkt_lang, and otherwise
it returns tx.Text.
select
decode(tx.Text,NULL,fs.anlageschwerpunkt_lang,tx.Text) Anlageschwerpunkt_1 from
POI.Fondsstamm fs,
Texte tx,
Texttypstamm txy
where
tx.match='amfcomm'
and tx.match=rtrim(fs.match)
and tx.TEXTTYPID=txy.TEXTTYPID
and txy.BEREICHSID=14
and txy.texttyp='Marketingstrategie'
I hope somebody of you can help me
thanxx
Schoeib

Answer 1

I read Schoeibs question differently; no ROWS are being returned. In that case you cannot expect DECODE or any other function to do anything. Assuming that rows always exist in fs and txy and are only missing in tx, then you need an outer join. Note that the join of tx.match = rtrim(fs.match) has been altered to avoid outer joining to more than one table. As mentioned before, although the decode is OK, NVL could be used instead.
select
decode(tx.Text,NULL,fs.anlageschwerpunkt_lang,tx.Text) Anlageschwerpunkt_1 from
POI.Fondsstamm fs,
Texte tx,
Texttypstamm txy
where
tx.match(+)='amfcomm'
and rtrim(fs.match) = 'amfcomm'
and tx.TEXTTYPID(+)=txy.TEXTTYPID
and txy.BEREICHSID=14
and txy.texttyp='Marketingstrategie'