MySQLDB.java

package databaseDemo;

import java.sql.*; // Step-1

public class MySQLDB implements Database {

    // Step-2
    // JDBC driver name and database URL
    static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    static final String DB_URL = "jdbc:mysql://localhost/javaDB";

    // Database credentials
    static final String USER = "root";
    static final String PASS = "";

    Connection conn = null;
    Statement stmt = null;

    @Override
    public void connectDB() throws ClassNotFoundException, SQLException {
        // STEP 3: Register JDBC driver
        Class.forName(JDBC_DRIVER);

        // STEP 4: Open a connection
        System.out.println("Connecting to database...");
        conn = DriverManager.getConnection(DB_URL, USER, PASS);
    }

    @Override
    public void query(String sql) throws SQLException {
        try {
            connectDB();
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // STEP 5: Execute a query
        System.out.println("Creating statement...");
        stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery(sql);

        // STEP 6: Extract data from result set
        while (rs.next()) {
            // Retrieve by column name
            int id = rs.getInt("room_id");
            String name = rs.getString("room_name");

            // Display values
            System.out.print(" room_id: " + id);
            System.out.println(" room_name: " + name);

        }

        // STEP 7: Clean-up environment
        rs.close();
        stmt.close();
        conn.close();
    }

}