I have a project wherein i have to take the CardID of an RFID as input. The problem i m facing is that I dont want the values of the cardid to be repeated so i want to have a case where the system compares the value of the new cardid and compare it with the previous value. If it is same, the new value should be discarded else it should be written in the database.
I tried using the OLDVALUE command but i was not sure of the syntax.
Kindly help me out.