🔐 User Authentication System — PN Solutions

A console-based User Authentication & Profile Management System built with Core Java and MySQL via JDBC. This project enables secure user registration, login, profile management, and account deletion — all through an interactive command-line interface.

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🚀 Features

✔ User Registration — New users can sign up with name, email, username, and password with data stored directly to MySQL.
✔ Secure Login — Authenticates user credentials against the database using parameterized queries.
✔ View Profile — Displays the logged-in user's complete profile details post-login.
✔ Update Profile — Allows users to modify their name, email, username, and password.
✔ Delete Account — Permanently removes user account with a confirmation prompt before deletion.
✔ User Dashboard — Clean post-login menu to navigate all profile actions seamlessly.
✔ Logout — Safely exits the current user session back to the home screen.

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🛠️ Technologies Used

• Java (JDK 8+): Core application logic, OOP design, and console I/O handling.
• MySQL 8.x: Relational database for persistent user data storage.
• JDBC: Java Database Connectivity using com.mysql.cj.jdbc.Driver for DB operations.
• PreparedStatement: Parameterized SQL queries to prevent SQL injection.
• OOP Design: Inheritance-based architecture — all DB classes extend DBconnection.

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📂 Project Structure

• HomePage.java — Entry point; displays main menu (Register / Login / Exit).
• RegisterUser.java — Handles new user registration and inserts data into the database.
• LoginPage.java — Authenticates credentials and launches the user dashboard on success.
• Dashboard.java — Post-login hub for View, Update, Delete, and Logout operations.
• updateProfile.java — Updates user profile fields in the database by username.
• DeleteProfile.java — Deletes user account from the database with confirmation.
• DBconnection.java — Base class providing reusable MySQL connection via JDBC.
• query.sql — SQL script to create the user_db database and users table.

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🗄️ Database Setup

Run the following SQL script in your MySQL client (also available in query.sql):

-- Create Database
CREATE DATABASE user_db;

-- Use Database
USE user_db;

-- Create Users Table
CREATE TABLE users (
    id         INT PRIMARY KEY AUTO_INCREMENT,
    name       VARCHAR(50)   NOT NULL,
    email      VARCHAR(100)  UNIQUE NOT NULL,
    username   VARCHAR(50)   UNIQUE NOT NULL,
    password   VARCHAR(100)  NOT NULL,
    created_at TIMESTAMP     DEFAULT CURRENT_TIMESTAMP
);

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⚙️ Configuration

Open DBconnection.java and set your MySQL credentials:

private String url      = "jdbc:mysql://localhost:3306/user_db";
private String username = "your_mysql_username";
private String password = "your_mysql_password";

⚠️ Security Note: Never push real credentials to version control. Use environment variables or a config.properties file and add it to .gitignore.

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🖥️ Application Flow

HomePage (Main Menu)
│
├── [1] Register ──────────► RegisterUser
│                                 └── Inserts into MySQL → Optional Login redirect
│
├── [2] Login ─────────────► LoginPage
│                                 └── Authenticates → Dashboard
│                                           ├── [1] View Profile
│                                           ├── [2] Update Profile ──► updateProfile
│                                           ├── [3] Delete Account ──► DeleteProfile
│                                           └── [4] Logout
│
└── [3] Exit

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📖 Learning Outcomes

This project demonstrates proficiency in:

• Java OOP principles — inheritance, encapsulation, and class design.
• JDBC connectivity — establishing and managing MySQL connections from Java.
• CRUD operations — Create, Read, Update, Delete via SQL with PreparedStatements.
• Console-based UI design — building interactive menu-driven applications.
• Database schema design — relational table creation with constraints and timestamps.

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👤 Author

Pravin PR
🏢 PN Solutions
📍 Tamil Nadu, India

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💡 This project is built for educational purposes to demonstrate Java-MySQL integration using JDBC. For production use, implement password hashing (BCrypt), input validation, and secure credential management.