Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE Order_items (product_id VARCHAR, order_id VARCHAR)
### Question:
Show the product ids and the number of unique orders containing each product.
### Answer:
SELECT product_id, COUNT(DISTINCT order_id) FROM Order_items GROUP BY product_id