MySQL Database Connection - Java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.ResultSet;
import java.sql.Statement;

public class MySQLConnection {

    // Connection parameters
    private static final String URL = "jdbc:mysql://localhost:3306/school_db";
    private static final String USER = "root";
    private static final String PASSWORD = "password";

    public static Connection connect() {
        """Connect to MySQL database with error handling"""

        Connection connection = null;

        try {
            // Load MySQL JDBC driver
            Class.forName("com.mysql.cj.jdbc.Driver");

            // Establish connection
            connection = DriverManager.getConnection(URL, USER, PASSWORD);
            System.out.println("✅ Connected to MySQL database successfully");

        } catch (ClassNotFoundException e) {
            System.err.println("❌ MySQL JDBC Driver not found: " + e.getMessage());
        } catch (SQLException e) {
            System.err.println("❌ Connection failed: " + e.getMessage());
        }

        return connection;
    }

    public static boolean testConnection(Connection connection) {
        """Test if connection is active"""
        if (connection != null) {
            try {
                Statement statement = connection.createStatement();
                ResultSet resultSet = statement.executeQuery("SELECT DATABASE()");

                if (resultSet.next()) {
                    String dbName = resultSet.getString(1);
                    System.out.println("📊 Current database: " + dbName);
                }

                resultSet.close();
                statement.close();
                return true;

            } catch (SQLException e) {
                System.err.println("❌ Error testing connection: " + e.getMessage());
            }
        }
        return false;
    }

    public static void closeConnection(Connection connection) {
        """Safely close database connection"""
        if (connection != null) {
            try {
                connection.close();
                System.out.println("🔌 MySQL connection closed");
            } catch (SQLException e) {
                System.err.println("❌ Error closing connection: " + e.getMessage());
            }
        }
    }

    public static void main(String[] args) {
        // Connect to database
        Connection conn = connect();

        if (conn != null) {
            // Test connection
            testConnection(conn);

            // Your database operations here

            // Close connection
            closeConnection(conn);
        }
    }
}

🛠️ Connection Parameters

Parameter	Example	Description
URL	jdbc:mysql://localhost:3306/school_db	JDBC connection string
USER	root	MySQL username
PASSWORD	password	MySQL password
DRIVER	com.mysql.cj.jdbc.Driver	MySQL JDBC driver class

🔧 Connection String Variations

With SSL Configuration

private static final String URL = 
    "jdbc:mysql://localhost:3306/school_db?useSSL=false&serverTimezone=UTC";

Remote Database

private static final String URL = 
    "jdbc:mysql://your-server.com:3306/production_db?useSSL=true";

With Connection Pool

// Using HikariCP connection pool
HikariConfig config = new HikariConfig();
config.setJdbcUrl("jdbc:mysql://localhost:3306/school_db");
config.setUsername("root");
config.setPassword("password");

HikariDataSource dataSource = new HikariDataSource(config);
Connection connection = dataSource.getConnection();

⚠️ Common Errors & Solutions

Exception	Cause	Solution
ClassNotFoundException	MySQL driver not in classpath	Add MySQL connector JAR
SQLException: Access denied	Wrong credentials	Check username/password
SQLException: Unknown database	Database doesn't exist	Create database first
CommunicationsException	Server not running/port blocked	Start MySQL, check firewall

📚 Dependencies (Maven)

<dependencies>
    <!-- MySQL Connector -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.33</version>
    </dependency>

    <!-- Connection Pool (Optional) -->
    <dependency>
        <groupId>com.zaxxer</groupId>
        <artifactId>HikariCP</artifactId>
        <version>5.0.1</version>
    </dependency>
</dependencies>

📚 Dependencies (Gradle)

dependencies {
    // MySQL Connector
    implementation 'mysql:mysql-connector-java:8.0.33'

    // Connection Pool (Optional)
    implementation 'com.zaxxer:HikariCP:5.0.1'
}

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