how do I get an e-mail when a field is updated?

how do I get an e-mail when a field is updated?

I have a form with multiple fields. I'd like to get an e-mail anytime one or more of the fields are changed and SAVED.

However, I would ALSO like the e-mail to say:

1. Which fields were updated (what they previously were and what they currently are)
2. Give me a link to that particular data-set

I know how to send the e-mail on update, but I don't know how to pull out the variables that tell me the above 2 listed items.

Any help? thanks!

- Quan