Write a SQL query to find the second-highest salary from an Employee table without using LIMIT. Given a Sales table with Date, Product_ID, and Revenue,

Write a SQL query to find the second-highest salary from an Employee table without using LIMIT.

• Given a Sales table with Date, Product_ID, and Revenue, write a query to find the cumulative revenue per product over time.
• Design a normalized database schema for an e-commerce application handling customers, orders, and payments.
• Implement a stored procedure to automatically update product stock levels after a purchase.