The primary goal of this project is to practice working with relational databases. You will design a well-structured database schema, manage relationships between tables (Primary and Foreign Keys), and connect a Java application to a PostgreSQL database to perform CRUD operations.

You will implement a backend system where users can create accounts, view the restaurant's menu, place orders, and store all transaction data permanently in a database.

Tech Stack:

Language: Java 23
Build Tool: Maven
Database: PostgreSQL
API: JDBC

✅ Prerequisites

Before starting, ensure you have the following installed on your machine:

Git
Java 23 (JDK)
Maven
PostgreSQL
A PostgreSQL Database GUI (e.g., pgAdmin, DBeaver, or DataGrip)

⚙️ Maven Configuration

This project relies on Maven to manage dependencies. Your project must contain a pom.xml file configured for Java 23 and the PostgreSQL JDBC driver.

Example pom.xml snippet:

XML

<properties>
    <maven.compiler.source>23</maven.compiler.source>
    <maven.compiler.target>23</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <postgresql.version>42.7.8</postgresql.version>
</properties>

<dependencies>
    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>${postgresql.version}</version>
    </dependency>
</dependencies>

🎯 Objectives

By completing this assignment, you will be able to:

Design a structured relational database schema.
Understand and implement database relationships (One-to-Many).
Work effectively with Primary Keys (PK) and Foreign Keys (FK).
Write SQL scripts to create tables and insert initial data.
Connect a Java application to PostgreSQL using JDBC.
Implement CRUD (Create, Read, Update, Delete) operations via Java.
Build a modular and object-oriented backend application.

🏗️ Database Entities & Schema

Your database must be created via a database.sql script. This file must include all CREATE TABLE statements, keys, constraints, and initial mock data.

Here are the required entities:

1. User (Customer)

Represents a customer using the system.

id: SERIAL PRIMARY KEY
username: VARCHAR (Required, UNIQUE)
password: TEXT (Required, stored as a hashed value)
email: VARCHAR (Optional)
Relationship: A User can have many Orders (1-to-N).

2. MenuItem

Represents the food/drink items available in the restaurant.

id: SERIAL PRIMARY KEY
name: VARCHAR (Required)
description: TEXT (Optional)
price: NUMERIC or DECIMAL (Required, must be strictly positive)
category: VARCHAR (Optional)
Requirement: You must pre-populate this table with at least 3 items using INSERT statements in your SQL file.

3. Order

Represents a specific order placed by a customer.

id: SERIAL PRIMARY KEY
userId: FOREIGN KEY (References User.id)
createdAt: TIMESTAMP (Default to current time)
totalPrice: NUMERIC or DECIMAL
Relationship: An Order belongs to one User. An Order contains many OrderDetails (1-to-N).

4. OrderDetail

Acts as a bridge table storing the specific items and quantities inside a single order.

id: SERIAL PRIMARY KEY
orderId: FOREIGN KEY (References Order.id)
menuItemId: FOREIGN KEY (References MenuItem.id)
quantity: INTEGER (Must be > 0)
price: NUMERIC (Snapshot of the item's price at the time of purchase)

💻 Required Features & App Flow

You must create a Java application that communicates solely with PostgreSQL using JDBC. Do not store any application data in local text files.

Feature 1: User Management (Auth)

Register: Insert a new user. Verify the username is unique and hash the password before saving.
Login: Validate credentials against the database. Handle incorrect username or password scenarios gracefully.

Fetch and display all available MenuItem records from the database.

Feature 3: Order Creation

Allow the logged-in user to select items from the menu and specify a quantity.
Calculate the total price.
Save the Order record, and subsequently save the corresponding OrderDetail records.

Feature 4: Receipt Generation

After an order is placed, query the database to print a detailed receipt.
Must include: Item names, quantities, unit prices, subtotal per item, and the final grand total.

Feature 5: Order History (Bonus ⭐)

Allow a user to view all their past orders and the total amount spent on each.

To give you an idea of how your application should flow, here is a recommended structure for your Command Line Interface :

Plaintext

=======================================
      🍕 WELCOME TO JAVA PIZZERIA 🍕
=======================================
1. Login
2. Register New Account
3. Exit
=======================================
Choose an option: 1

[Login]
Enter username: ***
Enter password: ***

=======================================
          🍽️ MAIN MENU 🍽️
=======================================
1. View Menu
2. Place a New Order
3. View Order History (Bonus)
4. Logout
=======================================
Choose an option: 2

[Placing Order]
Available Items:
1. Pizza - $10.00
2. Burger - $8.00
3. Pasta - $12.00

Enter the ID of the item to add (or 0 to finish): 1
Enter quantity: 2
Added 2x Pizza to your cart.

Enter the ID of the item to add (or 0 to finish): 0

[Order Summary / Receipt]
---------------------------------------
Item         Qty     Unit      Total
---------------------------------------
Pizza        2       $10.00    $20.00
---------------------------------------
Final Total: $20.00
Order saved successfully!

📃 Evaluation Criteria

Your project will be graded based on the following:

1. Database Design:

Correct schema design with appropriately chosen data types.
Proper use of Primary Keys, Foreign Keys, and Constraints (e.g., NOT NULL, UNIQUE).
A working database.sql initialization script.

2. JDBC Integration:

Successful connection to PostgreSQL.
Use of PreparedStatement to prevent SQL injection.
Proper exception handling (SQLException).

3. Code Quality & OOP:

Clean structure (e.g., separating database logic into DAO classes).
Avoidance of code duplication.
Application successfully covers all required functionalities (Auth, Menu, Ordering, Receipts).

README.md

WS-10-Database

🍕🗄️ Restaurant Database Management System

📖 Overview