How to Create a Dropdown list populated with db data

I have a SQL database on AWS. In WordPress I would like to create a Custom Field (or Fields) that are populated with data from my db table. For example, I would like the user to be able to Select from a Field called “State”. So to be clear, this is not a menu, it would be similar to a Combo Box.
I have a number of different options that the user would select so I don’t want to use a form with a bunch of radio buttons to choose from. That would just clutter the page.