"Not in" subquery

[Quoted] Is there any alternative query to the below one?

update RTable set Reason = "XYZ"

            Where FKey = 1234
                and SFKey = 1
                and Reason Is Null
                and F_ID  not in ( Select F_ID from RTable
                                    Where FKey = 1234
                                    and SFKey = 1
                                    and TO_NUMBER(REL_CD) = 1
                                    and Reason Is Null);

"not in" in the above query is taking alot of time and it is timing out.

Please Advise.

Thanks Received on Wed Jun 06 2007 - 22:23:09 CEST