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. 1.2. Using the IN clause, what are the names of the sellers who order 'X' and 'Y' products? 1.3. What are the names of the products that are ordered more than the average order (quantity x price) of the products