**Course Title:** Comprehensive Java Programming: From Basics to Advanced Concepts **Section Title:** Database Connectivity with JDBC **Topic:** Write a Java program that connects to a database, performs CRUD operations, and handles exceptions.(Lab topic) In this lab topic, we will create a Java program that connects to a relational database, performs CRUD (Create, Read, Update, Delete) operations, and handles exceptions using JDBC. We will use MySQL as our relational database, but you can easily adapt the code to work with other databases. **Prerequisites:** Before we start, make sure you have: 1. A relational database management system (RDBMS) like MySQL installed on your local machine. 2. A Java Development Kit (JDK) installed on your system, version 8 or higher. 3. An IDE like Eclipse, IntelliJ IDEA, or NetBeans. 4. The JDBC driver for MySQL downloaded and added to your project's classpath. **Step 1: Create a Database Connection** First, we need to create a database connection using JDBC. We'll create a utility class called `DBConnectionUtil` to handle this: ```java import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class DBConnectionUtil { private static final String DB_URL = "jdbc:mysql://localhost:3306/mydatabase"; private static final String DB_USERNAME = "username"; private static final String DB_PASSWORD = "password"; public static Connection getConnection() { try { Class.forName("com.mysql.cj.jdbc.Driver"); return DriverManager.getConnection(DB_URL, DB_USERNAME, DB_PASSWORD); } catch (ClassNotFoundException | SQLException ex) { System.out.println("Error connecting to database: " + ex.getMessage()); return null; } } } ``` **Step 2: Create a Table and Perform CRUD Operations** Next, we'll create a table called `employees` and perform CRUD operations using JDBC. We'll create a utility class called `EmployeeDAO` to handle this: ```java import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class EmployeeDAO { private Connection connection; public EmployeeDAO(Connection connection) { this.connection = connection; } public void createEmployee(int id, String name, double salary) { try (PreparedStatement statement = connection.prepareStatement("INSERT INTO employees (id, name, salary) VALUES (?, ?, ?)")) { statement.setInt(1, id); statement.setString(2, name); statement.setDouble(3, salary); statement.executeUpdate(); } catch (SQLException ex) { System.out.println("Error creating employee: " + ex.getMessage()); } } public Employee readEmployee(int id) { try (PreparedStatement statement = connection.prepareStatement("SELECT * FROM employees WHERE id = ?")) { statement.setInt(1, id); try (ResultSet resultSet = statement.executeQuery()) { if (resultSet.next()) { return new Employee(resultSet.getInt("id"), resultSet.getString("name"), resultSet.getDouble("salary")); } } } catch (SQLException ex) { System.out.println("Error reading employee: " + ex.getMessage()); } return null; } public void updateEmployee(int id, String name, double salary) { try (PreparedStatement statement = connection.prepareStatement("UPDATE employees SET name = ?, salary = ? WHERE id = ?")) { statement.setString(1, name); statement.setDouble(2, salary); statement.setInt(3, id); statement.executeUpdate(); } catch (SQLException ex) { System.out.println("Error updating employee: " + ex.getMessage()); } } public void deleteEmployee(int id) { try (PreparedStatement statement = connection.prepareStatement("DELETE FROM employees WHERE id = ?")) { statement.setInt(1, id); statement.executeUpdate(); } catch (SQLException ex) { System.out.println("Error deleting employee: " + ex.getMessage()); } } } class Employee { private int id; private String name; private double salary; // Constructor, getters, and setters } ``` **Step 3: Handle Exceptions** We'll handle exceptions using try-catch blocks. We'll also use the `finally` block to close the database connection: ```java public class Main { public static void main(String[] args) { Connection connection = DBConnectionUtil.getConnection(); if (connection != null) { try { EmployeeDAO employeeDAO = new EmployeeDAO(connection); employeeDAO.createEmployee(1, "John Doe", 5000.0); Employee employee = employeeDAO.readEmployee(1); if (employee != null) { System.out.println("Employee found: " + employee.getName()); } employeeDAO.updateEmployee(1, "Jane Doe", 6000.0); employeeDAO.deleteEmployee(1); } catch (SQLException ex) { System.out.println("Error: " + ex.getMessage()); } finally { try { connection.close(); } catch (SQLException ex) { System.out.println("Error closing connection: " + ex.getMessage()); } } } } } ``` **Conclusion:** In this lab topic, we created a Java program that connects to a relational database, performs CRUD operations, and handles exceptions using JDBC. We used MySQL as our relational database, but you can easily adapt the code to work with other databases. Remember to always handle exceptions and close the database connection to prevent resource leaks. **Additional Resources:** * MySQL JDBC Driver: [https://dev.mysql.com/downloads/connector/j/](https://dev.mysql.com/downloads/connector/j/) * JDBC Tutorial: [https://www.tutorialspoint.com/jdbc/index.htm](https://www.tutorialspoint.com/jdbc/index.htm) * Java 8 API Documentation: [https://docs.oracle.com/javase/8/docs/api/](https://docs.oracle.com/javase/8/docs/api/) **Comments and Questions:** Please leave a comment or ask a question if you need help or have feedback on this lab topic. Next, we will be discussing "Introduction to Java for web applications: Servlets and JSP" in the following topic: **Introduction to Java for web applications: Servlets and JSP** from **Web Development with Java**.