1. Queries in Relational Algebra and SQL Consider the order database of a retail company: customers (id.customer -> customerName, address, PostalCode, contact) products (id.Product -> ProductName, price, quantityStock) salespeople (id.Salesperson -> SalespersonName, contact, commission) orders (id.Order ->id.Customer, id.Salesperson, date) order_lines (id.Order, id.Line -> id.Product, quantity) . Express the following queries in SQL. Also avoid the clauses WITH, TOP and LIMIT: 1.1. Using the UNION operator, what are the names of customers who ordered 'X' and 'Y' products