I am sorry I misunderstood the whole thing and I sent you the opposite answer.

This is my query then:

SELECT S.IIATransactionId

 ,substring(rats_filename,1+patindex('%{________-____-____-____-____________}%',rats_filename),36) AS OracleTransactionId

FROM iiafeedtransaction S,

ratsiiafeedtransaction o

WHERE S.IIATransactionId *= substring(rats_filename,1+patindex('%{________-____-____-____-____________}%',rats_filename),36)

AND  o.Rats_filename IS NULL

AND S.IIATransactionId Not In  (SELECT substring(rats_filename,1+patindex('%{________-____-____-____-____________}%',rats_filename),36) FROM ratsiiafeedtransaction)

ORDER BY S.IIATransactionId

which I am pretty sure you figured it out.