Overwriting a record with part of same primary key
Could anyone please give a suggestion about how to overwrite the record with part of same primary key?
I have 5 key fields.
I have to overwrite the record if A5 changes with same A1 A2 A3 A4.
I cannot take off A5 as part of primary key. If I use modify or insert, its creating a new record with the new A5. But I am still having the old record in the table (with old A5), which I don't want it to be there.