servlet example without using MVC pattern

[Shanu Pandey]

I have written the following Servlet for Login Page without using MVC pattern:
Correct UserNames and Passwords are stored in MSAccess Database.

package com.ducat.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import javax.servlet.*;
import javax.servlet.http.*;

public class P extends HttpServlet {
    private static final String CONTENT_TYPE = "text/html; charset=windows-1252";
  public void init(ServletConfig config) throws ServletException {
        super.init(config);
    }

    public void doPost(HttpServletRequest request,
                       HttpServletResponse response) throws ServletException,
                                                            IOException {
        response.setContentType(CONTENT_TYPE);
        PrintWriter out = response.getWriter();
        try{
            
        String dataSourceName = "ddsn";
        String dbURL = "jdbc:odbc:" + dataSourceName;
        Connection con = DriverManager.getConnection(dbURL, "",""); 
        Statement s = con.createStatement();
        
        String name = request.getParameter("username"); 
        String password = request.getParameter("password");
        
        name = name.trim();
        password=password.trim();    
        
        s.execute("select * from Table2 ");
        ResultSet rs = s.getResultSet();

        if (rs != null) 
        while ( rs.next() )
        {
               
                if((!(name.equals ("null")) && name.equals(rs.getString ("username"))) && (!(password.equals ("null")) && password.equals(rs.getString ("password"))))
                {
                  response.sendRedirect("m.html");
                }
            else
                {
                  out.println("Invalid UserName or Password");
                }
            
        }   
        out.close();
    }
        catch(Exception e){
                 out.println(e);
        }
        }
}

The problem is this ..when I enter wrong UserName and Password, it prints ‘Invalid UserName or Password’ many times.But I want it only once.How to overcome this problem.please help me to make correction in the code.

[Ben Souther]

You're selecting every name in the table and then comparing them in your Java code.
Why not build a select statement that looks for the exact username and password entered by the user.

If you have an empty resultSet, then you know there was no match.