Noob question about forms in Base

I’m creating a database and in an item entry form, I’d like to have a dropdown for “Category” and for “Sub-Category”. I would like to have the “Sub-Category” dropdown options dependent on which “Category” is selected. (There are many categories and sub-categories to choose from) How would I set that up?

With dropdown this is only possible by macro: Hierachical listboxes, Chapter 9 Macros

Without dropdown you could get the behavior with main-form and sub-form. The form shows the category and the sub-form sub-categories for the main-category of the main-form.

This APPARENTLY works.
REM: DB is the same of Warning message in Forms.
And there there is a @Villeroy 's solution without code, via Filter Table method.
ListBoxUpdated

I’m very often using filter tables. But without a macro you have to
→ save the value in filter table and
→ refresh the listbox (putting cursor in listbox and choose refresh control from navigation bar)