How to add multiple entries from one list in the dropdown menu to another in the database?

Ex: I have a list of states that the user would like to travel. I pull this list from a dropdown menu connected to the bank (states). he chooses the state! and then enable a list of cities from that country in another dropdown. connected to the bank (cities) … how could you make the user choose more than one city or municipality in that state?

i have 3 databases one for the states and one for cities. and one for the user.
where are your preferences and fields name, email, countries and cities of your choice.

how could you make the user choose more than one city or municipality in that state?

You can’t to it with a regular dropdown element.
So either use checkbox group instead, or create a dropdown of your own using a box and text boxes (then you can do whatever you want using code).

See the Checkbox Dropdown example.