An e-commerce company wants to keep an audit trail. Every time a price is updated in the Products table, the old price and the time of change must be saved into a Price_History table automatically. Which SQL object is designed for this?
You have an Employees table with columns emp_id, name, and manager_id. Which SQL technique is required to generate a list of all employees alongside the name of their direct manager in a single result set?
A bank wants a list of customers who have a "Savings Account" but do not have a "Credit Card". Both accounts are stored in the Accounts(cust_id, type) table. Which set operator is most appropriate?