Update mySQL DB

Hi,


I have created a custom form and configured the Submission Actions to save the form contents to a mySQL DB. Using an Asset Listing Page and a DB data source, I am able to display the results.



Now, I would like to be able to update the record(s) by using a custom form.



I assume that I could use the the SQL UPDATE statement in the Submission Actions to update the values of a particular record. But how can I populate the form fields values of the custom form, with the record fields form the DB?



Is there a way to achieve this?



Many Thanks