Conditional aggregation in SQL
SQL interview exercise on Aggregation, difficulty 2 of 3. Solve it in the editor beside a worked example; the tests run the moment you do.
For each category return how many products are in stock (stock above 0) and how many are out of stock. Every category appears, even with a 0. Columns: category, in_stock, out_of_stock. Sorted by category.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Progress is saved in your browser, and in your account if you sign in.