How to make custom column dropdown based on other column?

[slb]

Hi

I have many genres in my library. Now I use one hierarchy column, but it is a very messy sight. So I'd like to set op this scenario:

Custom column 1: 'Main Genre'
=> with dropdown list: Romance, Action, Adventure, Horror...

This I know how to do.

Custom column 2: 'Sub Genre'
=> with specific dropdown values in list
=> able to select multiple values

Example 1:
Main Genre = Romance
Sub Genre specific dropdown: Time Travel, Fantasy, ...

Example 2:
Main Genre = Science Fiction
Sub Genre specific dropdown: Space Opera, Aliens, ...

How do I make this column?

Thanks in advance

[ownedbycats]

I don't think the dropdown is possible.

What I personally do, I have #booktype (enumerated dropdown), Fiction, Nonfiction, Magazines & Publications, etc. Then I have tags, which is Fiction.Romance, Magazines & Publications.Brochures. Then I use this composite column:

program:

tags = $tags;
booktype = strcat($#booktype, '.');

list_re(tags, ',', booktype, ',')

So for a book with type Fiction and tag Fiction.Mystery, it displays the column as 'Mystery.'