title: How to use the md5 hash?
body: <p>Okay, so I'm learning php, html, and mysql to learn website development (for fun). One thing I still don't get is how to use md5 or sha1 hashes. I know how to hash the plain text, but say I want to make a login page. Since the password is hashed and can't be reversed, how would mysql know that the user-inserted password matches the hashed password in the database? Here is what I mean:</p>
  
  <pre><code>$password = md5($_POST['password']);
  $query = ("INSERT INTO `users`.`data` (`password`) VALUES ('$password')");
  </code></pre>
  
  <p>I know that this snippet of script hashes the password, but how would I use this piece of code and make a login page? Any working examples would be great. </p>
  
  <p>Here is my script:</p>
  
  <pre><code>&lt;?php  
  
  session_start();  
  
  include("mainmenu.php");  
  
  $usrname = mysql_real_escape_string($_POST['usrname']); 
  $password = md5($_POST['password']);  
  
  $con = mysql_connect("localhost", "root", "g00dfor@boy"); 
  
  if (!$con) {    
     die(mysql_error()); }  
  
  mysql_select_db("users", $con) or die(mysql_error());  
  
  $login = "SELECT * FROM `data` WHERE (`usrname` = '$usrname' AND `password` = '$password')"; 
  
  $result = mysql_query($login);  
  
  
  if (mysql_num_rows($result) == 1) {     
  
  $_SESSION['logged_in'] = true;   
    header('Location: indexlogin.php');  
  
  exit; 
  
  } 
  
  else {     
  echo "Wrong username or password."; 
  
  }  
  
  ?&gt; 
  </code></pre>
  
  <p>But I still get the else statement, "Wrong username or password. Someone help plz!"</p>