# WS 10 - Restaurant Database Management System

![postgres_db.png](postgres_db.png)

## 📖 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 using a `database.sql` script.

The script must include:

* Table creation statements
* Keys and relationships
* Appropriate constraints
* Initial mock data

You are responsible for selecting appropriate:

* Data types
* Primary Keys
* Foreign Keys
* Constraints (e.g., `NOT NULL`, `UNIQUE`, `CHECK`, `DEFAULT`)

Your design decisions will be evaluated as part of the assignment.

---

### 1. User (Customer)

Represents a customer using the system.

Required Information:

* Unique identifier
* Username
* Password
* Email (optional)

Requirements:

* Usernames must be unique.
* Passwords must not be stored in plain text.
* A user can place multiple orders.

---

### 2. MenuItem

Represents a food or drink available in the restaurant.

Required Information:

* Unique identifier
* Name
* Description (optional)
* Price
* Category (optional)

Requirements:

* Every item must have a positive price.
* The database must contain at least 3 menu items inserted through the SQL script.

---

### 3. Order

Represents a specific order placed by a customer.

Required Information:

* Unique identifier
* Reference to the customer who placed the order
* Creation date and time
* Total price

Requirements:

* An order belongs to exactly one user.
* A user can have multiple orders.
* An order can contain multiple items.

Note:
Order is a reserved SQL keyword in many database systems.
Choose an appropriate table name such as `orders` if needed.

---

---

### 4. OrderDetail

Represents an item inside an order.

Required Information:

* Unique identifier
* Reference to an order
* Reference to a menu item
* Quantity
* Item price at the time of purchase

Requirements:

* Quantity must always be greater than zero.
* The stored price should represent the item's price when the order was placed.
* An order can contain multiple order details.

---

### Design Notes

Before implementing the schema, carefully design:

* The primary key of each entity.
* The foreign key relationships.
* Any uniqueness constraints.
* Any required fields.
* Any validation rules that should be enforced by the database.

Your schema should be normalized and designed to avoid unnecessary data duplication.

### Recommendation

Before writing any SQL, create a simple Entity Relationship Diagram (ERD) to visualize:

* Entities
* Primary Keys
* Foreign Keys
* Relationships between tables

This diagram does not need to be submitted, but it is strongly recommended as part of the database design process.

## 📁 Project Structure

A suggested structure for the project:

- model
    - Database entity classes

- database
    - PostgreSQL connection management classes

- dao
    - JDBC database access classes

- service
    - Application business logic

- ui
    - Console user interface

## 💻 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 

- 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 
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, keys, constraints, and relationships.
    
- 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, Order History).