The marketing team wants to identify customers who spent more on paid orders during the second half of May 2026 than during the first half.
Using orders, compare each customer's paid-order revenue across these two periods, measured in UTC:
01First half: May 1 through May 15, 2026, inclusive.
02Second half: May 16 through May 31, 2026, inclusive.
Include customers only when their second-half paid revenue is strictly greater than their first-half paid revenue. A customer with no paid orders in the first half has first-half paid revenue of 0, not NULL.
Only orders with status = 'paid' contribute to either amount. Refunded, delivered, cancelled, and other statuses do not count.
Ordering: Sort by customer_id in ascending order.