WS-11-Database

Restaurant Database Management System 🍕🗄️

Overview 👋

In this workshop, you will build a restaurant management system focused on database design, PostgreSQL, and JDBC integration.

The main goal of this project is to practice working with relational databases, designing a proper database schema, managing relationships between tables, and connecting a Java application to PostgreSQL.

You will implement a backend system where users can create accounts, view menu items, create orders, and store all information permanently inside a database.

The project should be implemented using:

• Java 23

• Maven

• PostgreSQL

• JDBC

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Prerequisites ✅

Make sure you have installed:

• Git

• Java 23

• Maven

• PostgreSQL

• PostgreSQL Client (pgAdmin is recommended)

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Maven Configuration

This project must use Maven as the build tool.

Your project should contain:

pom.xml

The pom.xml file is responsible for managing project dependencies and configuring the Java version.

You need to add the required PostgreSQL JDBC driver dependency.

Example:

<dependencies>

    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <version>42.7.3</version>
    </dependency>

</dependencies>

This dependency allows your Java application to connect to PostgreSQL using JDBC.

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Objectives ✏️

By completing this assignment, you will:

• Learn how to design a relational database

• Understand database relationships

• Work with Primary Keys and Foreign Keys

• Use SQL to create and manage tables

• Connect Java applications to PostgreSQL using JDBC

• Implement CRUD operations

• Handle database transactions

• Build a structured backend application

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Important Concepts

CRUD Operations

CRUD represents the four basic operations used to manage data in a database.

CRUD stands for:

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Create

Adding new records to the database.

Example:

INSERT INTO users(username, password)
VALUES ('ali', 'hashed_password');

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Read

Retrieving information from the database.

Example:

SELECT * FROM menu_items;

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Update

Changing existing information.

Example:

UPDATE users
SET email='new@email.com'
WHERE id=1;

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Delete

Removing records.

Example:

DELETE FROM menu_items
WHERE id=3;

Your application should support CRUD operations where appropriate.

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Database Entities

Your database must contain these entities:

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1. User

Represents a customer.

Attributes:

• id

  • Primary Key

• username

  • Required

  • Unique

• password

  • Stored as hashed value

• email

  • Optional

Relationship:

One user can have many orders.

User 1 -------- N Order

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2. MenuItem

Represents restaurant menu items.

Attributes:

• id

  • Primary Key

• name

• description

  • Optional

• price

• category

  • Optional

Requirement:

Database must contain at least 3 initial menu items.

Example:

Name	Price	Category
Pizza	10	Fast Food
Burger	8	Fast Food
Pasta	12	Italian

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3. Order

Represents a customer's order.

Attributes:

• id

  • Primary Key

• userId

  • Foreign Key

• createdAt

• totalPrice

Relationships:

User 1 -------- N Order

Order 1 -------- N OrderDetail

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4. OrderDetail

Stores each ordered item.

Attributes:

• id

  • Primary Key

• orderId

  • Foreign Key

• menuItemId

  • Foreign Key

• quantity

• price

Example:

Order:

Pizza x2
Burger x1

Stored as:

Order ID	Item	Quantity
1	Pizza	2
1	Burger	1

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Database Requirements

Create:

database.sql

This file must include:

• CREATE TABLE statements

• Primary Keys

• Foreign Keys

• Constraints

• Initial data

Example:

CREATE TABLE users(

id SERIAL PRIMARY KEY,

username VARCHAR(50) UNIQUE NOT NULL,

password TEXT NOT NULL

);

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Java + JDBC Requirements

Create a Java application that communicates with PostgreSQL using JDBC.

All data must be stored inside PostgreSQL.

Do not store application data in files.

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Required Features

User Management

The system must support:

Register User

Insert a new user.

Required:

• Username

• Password

• Email (optional)

Rules:

• Username must be unique

• Password must be hashed

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Login Validation

Check credentials from database.

Possible results:

• Login successful

• Username not found

• Wrong password

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Menu Management

Load menu items from database.

Example:

ID | Name | Price

1 | Pizza | 10
2 | Burger | 8
3 | Pasta | 12

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Order Management

Users should be able to create orders.

Process:

1. Select user

2. Select food items

3. Set quantity

4. Save order

Database example:

Order:

ID	User ID	Total
1	5	28

OrderDetail:

Order ID	Item	Quantity
1	Pizza	2
1	Burger	1

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Receipt Generation

After creating an order, retrieve the order information from database.

Receipt must include:

• Food name

• Quantity

• Unit price

• Item total price

• Final order price

Example:

Pizza

Quantity: 2
Unit Price: 10
Total: 20


Burger

Quantity: 1
Unit Price: 8
Total: 8


Final Price: 28

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Order History (Bonus)

Users can view previous orders.

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Database Rules

Required:

• Every table must have Primary Key

• Relationships must use Foreign Keys

• Username must be UNIQUE

• Required fields must be NOT NULL

• Price must be positive

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Transaction Requirement

Creating an order must use a database transaction.

Steps:

1. Insert Order

2. Insert OrderDetails

If any step fails:

Rollback the entire operation.

Example:

BEGIN TRANSACTION

Insert Order

Insert OrderDetails

COMMIT

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Evaluation Criteria 📃

Database Design

• Correct schema design

• Proper relationships

• Correct constraints

• SQL initialization file

JDBC Integration

• PostgreSQL connection

• Correct SQL queries

• PreparedStatement usage

• Exception handling

Functionality

The application must support:

• Creating users

• Login verification

• Reading menu items

• Creating orders

• Saving order details

• Generating receipts

• Viewing order history

Code Quality

The code should:

• Follow Object-Oriented principles

• Have clean structure

• Avoid duplicated code

• Separate database logic from application logic

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