Question: Creating Composite Index

Question

We have a database for a company that manages information about its employees, the product categories they handle, the products within those categories, and the sales made. The Employees table stores unique identifiers (EID), employee names, and ages. The ProductCategories table contains unique identifiers (CategoryID) for each category and assigns one employee to manage each. The Products table contains identifiers (PID) for each product, along with their respective categories, names, and prices. The Sales table keeps track of sales, recording a unique identifier (SalesID), the employee responsible, the product category, the sales amount, and the month of sale.