Can my forms do database lookups and retrieve results?

I want users to come to my site (i'll provide password authentication for their access), be able to make a selection of the city they live in, and the form will then automatically poulate with information that I have already stored in JotForm.  if the user wants to edit the form then re-submit the data, that will be OK.  I need them to be able to do a database lookup based on a drop down menu.  

is this possible in JotForm?

Unfortunately, database lookup is not possible in Jotform. You have to add that custom function in the form through the use of the form source codes.

https://www.jotform.com/help/104-How-to-get-the-Full-Source-Code-of-your-Form

I cannot provide you an example right now, but I'd be happy to look for one if you want.