Hi John

>I am trying to develop my application in n-tier model. Therefore, I use collection to store my data object.
>May be I am in the wrong way of doing thibg. Could you please share your knowledge on how you do what I mentioned with n-tier model?

I am not sure I understand what you mean. Surely this is a single tier operation? You want to compare the original set of data to a version that mayhave been modified.

That requires connections to both the User Interface and Database. However, within the tier it does not matter what you use (a collection, an array, a cursor or a view). The only issue is how you communicate the results of an operation between tiers.

Therefore when you retrieve the data, store it in a local cursor. When you receive the data back, update your local cursor directly and then use the OLDVAL() and CURVAL() functions to determine what changed on a record by record basis.