Supermarket Lite

In Module 2 (Object-Oriented Information Systems) of my master studies at the University of Essex I did an UML class diagram for a Supermaarket using StarUML. I wanted to push the project further so created this project to practice class diagram implementation in Python (OOP) and a database using SQL (MySQL and SQL Server).

The project is divided in three parts:

• Directory 1: source -> contains files with OOP in Python
• Directory 2: sql -> contains the normalization (3fn) of the database in two versions
• Directory 3: diagrams -> contains: a) EER diagram created with SQL Server, b) Class diagram created with StarUML

Directory 1: Source

• main.py -> tests
• people_db.py -> connects to MySQL using Python

Supermarket Lite has 7 CLASSES:

• customers.py
• loyaltyschemes.py
• payment.py
• people.py
• products.py
• shoppingcart.py
• staff.py

Directory 2: SQL

Contains the normalization (3fn) of the database in two versions: MySQL and SQL Server. The goal is to practice the syntax differece between these two tools.

Directory 3: Diagrams

a) EER diagram created in SQL Server

b) Class diagram created with StarUML

The class diagram has 8 classes. I have applied generalization, composition, aggregation, and direct association. Next, I describe the four different diagram relationships and indicate the classes of the Supermarket diagram that belong to each category.

Generalization/inheritance:

• People & Staff (the attributes listed in the class "People" are applied to the class Customers)
• People & Customers (the attributes listed in the class "People" are applied in the class Staff)

Composition:

• Customers & Shopping Cart (customer always has a shopping cart)
• Loyalty Schemes & Payment (loyalty schemes always create discounts in payments)
• Customers & Online Order (customers always have online orders)

Aggregation:

• Products & Shopping Cart (Products can be included in Shopping Carts)
• Shopping Cart & Online Orders (shopping carts can lead to payment or not because customer can give up)
• Customers & Payment (customers can finish payment or not)
• Customers & Loyalty Schemes (customers can have loyalty schemes or not)
• Online Orders & Payment (Online orders can lead to payment or not)

Direct Association: Refers to a directional relationship represented by a line with an arrowhead.

• Staff & Online Orders (Staff members manage Products)