I will try to be brief, I do not know if something like this is possible, I want to edit the values of a table, which is what is done with an update, but I want to allow editing those values compare the values that are stored, with the new ones, and if equal store them, otherwise do not allow to do it. I explain the reason; I'm going to store data from a transaction, but the administrator must authorize that transaction, but in order to authorize it should be able to enter the transaction number, and if it is the same then it is stored and authorization is allowed, if it is different then it is denied.