How do I count topics in sub-categories?

Here are some quick Data Explorer queries in case you need to do this more in the future.

Query to get topic count for one category (or subcategory).

-- [params]
-- null string_list :category_name
SELECT topic_count FROM categories
WHERE categories.name = :category_name

Query to list all categories (and subcategories) and their topic counts:

SELECT name, topic_count FROM categories