# WS 10 - Restaurant Database Management System


## 📖 Overview

In this workshop, you will build a **Restaurant Management System** focused on database design, PostgreSQL, and JDBC integration.

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.
    

### Feature 2: Menu Browsing

- 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.
    

## 📱 Sample Console Menu Template

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).