💻 Coding & Development Prompts

Write SQL queries for a database with tables: orders (id, customer_id, order_date, total), customers (id, name, email, city), products (id, name, price, category), order_items (order_id, product_id, quantity). Queries needed: 1) Top 10 customers by total spend, 2) Monthly revenue for last 12 months, 3) Best selling product per category, 4) Customers who ordered in January but not February, 5) Running total of sales by month (window function), 6) Products never ordered. Optimize for performance.