The following tables form part of a database held in a relational DBMS (Primary Key,Foreign Key):

Item (Item _ID, Item_Name, Item_Price)

Customer (Customer_No, L_Name, F_Name, Address, Type)

CustomerItem (Customer_No, Item_No, Date_Purchased)

Employee (Employee_No L_Name, F_Name, Role)

Provide the SQL for the following queries (5 marks each):

1. List the number of items purchased by "Retail" Customers
2. Show the customer(s) who have purchased more than five items (*Show the Customer_No only)
3. List the maximum number of items purchased by any customer
4. Show the "Wholesale" Customer(s) who have not purchased any item (*Show the Customer_No only)
5. List the full details of the most expensive as well as the cheapest item