Servlet Code for Updating Database Records
The servlet will receive id, name, and age parameters from the client, which it will use to update the name and age fields of a specific user in the database.

java
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import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/UpdateUserServlet")
public class UpdateUserServlet extends HttpServlet {

    private static final String DB_URL = "jdbc:mysql://localhost:3306/yourDatabaseName";
    private static final String DB_USER = "yourUsername";
    private static final String DB_PASSWORD = "yourPassword";

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // Get parameters from the request
        String id = request.getParameter("id");
        String name = request.getParameter("name");
        String age = request.getParameter("age");

        // Set response content type
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        Connection conn = null;
        PreparedStatement stmt = null;

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

            // Establish database connection
            conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);

            // Prepare the SQL update statement
            String sql = "UPDATE users SET name = ?, age = ? WHERE id = ?";
            stmt = conn.prepareStatement(sql);
            stmt.setString(1, name);
            stmt.setInt(2, Integer.parseInt(age));
            stmt.setInt(3, Integer.parseInt(id));

            // Execute update and check if a record was updated
            int rowsUpdated = stmt.executeUpdate();
            if (rowsUpdated > 0) {
                out.println("<h1>User updated successfully!</h1>");
            } else {
                out.println("<h1>User not found or update failed.</h1>");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
            out.println("<h1>Error: Unable to load database driver.</h1>");
        } catch (SQLException e) {
            e.printStackTrace();
            out.println("<h1>Error: Unable to execute update operation.</h1>");
        } finally {
            try {
                if (stmt != null) stmt.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}