Create the following Database Models and apply the concept of normalization when identifying database tables:

• Conceptual Model (using the Chen Notation [only entities and relationships])
• Logical Model (E.R. Modeling using Crow's Foot Notation) - do specify the Primary Key, Foreign Key(s), other Attributes

Problem:

A certain shop wants to have an inventory and sales management system. As of the moment, they would want a database that adheres to the following business rules:

1. A customer may generate many invoices. Each invoice is generated by one customer. A customer has a last name, first name, address, and a phone number. An invoice has a date of transaction.
2. An invoice contains one or more invoice lines. Each invoice line is associated with one invoice. An invoice line contains the product item, quantity, and total price.
3. Each invoice line references one product. A product may be found in many invoice lines. (You can sell more than one hammer to more than one customer.) A product has a description, restock date, quantity on hand, minimum no. of quantity, and price.
4. A vendor may supply many products. Some vendors do not yet supply products. For example, a vendor list may include potential vendors. A vendor has a name, contact number, and address.
5. If a product is vendor-supplied, it is supplied by only a single vendor. Some products are not supplied by a vendor. For example, some products may be produced in-house or bought on the open market.