task IN / EXISTS / NOT EXISTS · hard

Find shoppers in every category

Return shoppers who bought at least one item from every distinct category currently in catalog_items, considering only delivered orders.

what to return

Columns

shopper_idname in this order

Rows

1 row · in the order asked

Watch for

Derive the required category set from the catalog; do not hardcode four categories or named categories.

Multiple products and orders in one category count only once. Include every qualifying shopper and order by shopper_id.

This exercise adds two illustrative orders to the standard Harbor Market data; previews include them.

Skill

Find entities related to every member of a changing required set. Refresher: Multi-grain joins without fan-out →

expected result

Your query should return exactly these columns and values. Run it and compare.

data you can query

Sample rows from each table. Each column shows its type underneath; → marks a link to another table.