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import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;

public class UpdateEmailServlet extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // Get user input from request
        String userId = request.getParameter("id");
        String newEmail = request.getParameter("email");

        // Database connection parameters
        String jdbcUrl = "jdbc:mysql://localhost:3306/your_database";
        String dbUser = "your_username";
        String dbPassword = "your_password";

        Connection conn = null;
        PreparedStatement pstmt = null;

        try {
            // Step 1: Load the JDBC driver (optional in recent JDBC versions)
            Class.forName("com.mysql.cj.jdbc.Driver");

            // Step 2: Establish connection to the database
            conn = DriverManager.getConnection(jdbcUrl, dbUser, dbPassword);

            // Step 3: Create SQL update query
            String sql = "UPDATE users SET email = ? WHERE id = ?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, newEmail); // set email parameter
            pstmt.setInt(2, Integer.parseInt(userId)); // set id parameter

            // Step 4: Execute update
            int rowsUpdated = pstmt.executeUpdate();

            // Step 5: Handle response based on update result
            response.setContentType("text/html");
            PrintWriter out = response.getWriter();
            if (rowsUpdated > 0) {
                out.println("<h1>Email updated successfully for user ID: " + userId + "</h1>");
            } else {
                out.println("<h1>No user found with ID: " + userId + "</h1>");
            }

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                // Close resources
                if (pstmt != null) pstmt.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}
---<html>
  <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Update Email</title>
</head>
<body>
    <h2>Update User Email</h2>
    <form action="UpdateEmailServlet" method="POST">
        <label for="id">User ID:</label>
        <input type="text" id="id" name="id" required><br><br>
        
        <label for="email">New Email:</label>
        <input type="email" id="email" name="email" required><br><br>
        
        <input type="submit" value="Update Email">
    </form>
</body>
</html>
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