The workshop is designed to help you anticipate possible questions, review what you've learned, and begin learning how to put your knowledge into practice.
Which PHP function was used to uppercase the category title strings?
Why don't the store_item_size and store_item_color tables contain any primary or unique keys?
Presumably, you will have items with more than one color and more than one size. Therefore, item_id is not a primary or unique key. Also, items may have the same colors or sizes, so the item_color and item_size fields must not be primary or unique either.