VS 2010 compare two datasets

hi everyone,
hope you doing fine. I really need some help. actually i am developing a small application for creating invoices. one thing that i am finding really hard is when you have to edit an invoice. In my application, it generates an invoice number and you fill in the details such as description, qty, unit price and total amount. at first this is saved in the db, printed and shown to the head for approval. if there is any mistake, the user has to come back to the application and makes the changes for the invoice. this is where i am getting stuck. The application can recall the invoice. but once the changes made, i have to save it back to the db and this change can be for a specific record only. for instance,

invoice 001

serial descr qty unitprice total
1 paintx 2 2000 4000
2 painty 3 1000 3000
3 paintz 1 2000 2000

lets say there is a mistake and amendments to be done

serial descr qty unitprice total
1 paintx 2 2000 4000
2 painty 3 1000 3000
3 paintz 2 2000 4000

how am i supposed to make this change ?

any technique or logic i can use?

i was thinking of loading the invoice data in a dataset and then comparing it to the new data entered which is in a dataset also.

is that ok?

please advise.