What are the sql queries for the following based on the tables?

a) Produce list of product names that have never been ordered

b) Produce list of customer id that have never placed any orders

c) Produce list of all customer id, and number of different products they have ordered (sorted descending order by number of different products)

Productlt ProductName ProductNumber ProductLine ProductClass SALES ORDERS CUSTOMER SalesOrderNumber CustomerID OrderDate DueDate ShipDate SubTotal TaxAmt Freight TotalDue CustomerID CustomerType AddressLinel AddressLine2 Product Color PostalCode ProductlistPrice ProductSize ProductSizeUnitMeasureCode Productweight ProductWeightUnitMeasureCode ORDER_DETAILS SalesOrderDetailID SalesOrderNumber ProductID OrderQty UnitPrice UnitPriceDiscount LineTotal