Saving data to next page from custom database

I’m trying to collect data from the same user going through our site’s onboarding flow on different pages - it’s a form that collects the user’s data as they move on to the next page onto a database called user_training.

My options for “things to change” are the current user, which is not what I want to change (the data types I need to change are not under the User’s database but under a different one - user_training) or do a search for (which is probably where I would probably need a unique ID).

My question is, how do I:

  1. Search for the user in my data type
  2. Move across columns to change data types in that database?
  3. Would I need a unique user ID, or is there a way to generate one?

Any thoughts on how to do this? Also, what if the data for user_1 is saved in the first page, nothing is saved in the second page (transition page), and need to make changes to that user in page 3?

Thanks again!