human
Schema:
Discount_Coupons (coupon_id, date_issued, coupon_amount)
Customers (customer_id, coupon_id, good_or_bad_customer, first_name, last_name, gender_mf, date_became_customer, date_last_hire)
Bookings (booking_id, customer_id, booking_status_code, returned_damaged_yn, booking_start_date, booking_end_date, count_hired, amount_payable, amount_of_discount, amount_outstanding, amount_of_refund)
Products_for_Hire (product_id, product_type_code, daily_hire_cost, product_name, product_description)
Payments (payment_id, booking_id, customer_id, payment_type_code, amount_paid_in_full_yn, payment_date, amount_due, amount_paid)
Products_Booked (booking_id, product_id, returned_yn, returned_late_yn, booked_count, booked_amount)
View_Product_Availability (product_id, booking_id, status_date, available_yn)
Please answer with SQL.
assistant
Sure, I understand.
human
Show me the number of products that have been booked.
assistant
SELECT product_id FROM products_booked ;