What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Though you can take advantage of our "Import Data" app to import data from database to your form submission page but it is not possible to populate the field of your form from any external data source or from your form's previous submissions.
One possibility is to write a new page which will fetch the data from DB and then populate the form field by taking advantage of our "URL Parameter" feature. The following guide should help you: http://www.jotform.com/help/71-Prepopulating-fields-to-your-JotForm-via-URL-parameters
Hope this helps.
Do get back to us if you have any questions.