PHP Login Script Code and Tutorial

The Database

Before we can create a login script, we first need to create a database to store users. For the purpose of this tutorial we will simply need the fields "username" and "password", however, you can create as many fields as you wish.

 CREATE TABLE users (ID MEDIUMINT NOT NULL AUTO_INCREMENT PRIMARY KEY, username VARCHAR(60), password VARCHAR(60)) 

This will create a database called users with 3 fields: ID, username, and password.

Registration Page 1

 <?php
// Connects to your Database
mysql_connect("your.hostaddress.com", "username", "password") or die(mysql_error());
mysql_select_db("Database_Name") or die(mysql_error());
//This code runs if the form has been submitted
if (isset($_POST['submit'])) {
//This makes sure they did not leave any fields blank
if (!$_POST['username'] | !$_POST['pass'] | !$_POST['pass2'] ) {
die('You did not complete all of the required fields');
}
// checks if the username is in use
if (!get_magic_quotes_gpc()) {
$_POST['username'] = addslashes($_POST['username']);
}
$usercheck = $_POST['username'];
$check = mysql_query("SELECT username FROM users WHERE username = '$usercheck'")
or die(mysql_error());
$check2 = mysql_num_rows($check);
//if the name exists it gives an error
if ($check2 != 0) {
die('Sorry, the username '.$_POST['username'].' is already in use.');
}
//
this makes sure both passwords entered match
if ($_POST['pass'] != $_POST['pass2']) {
die('Your passwords did not match. ');
}
// here we encrypt the password and add slashes if needed
$_POST['pass'] = md5($_POST['pass']);
if (!get_magic_quotes_gpc()) {
$_POST['pass'] = addslashes($_POST['pass']);
$_POST['username'] = addslashes($_POST['username']);
}
// now we insert it into the database
$insert = "INSERT INTO users (username, password)
VALUES ('".$_POST['username']."', '".$_POST['pass']."')";
$add_member = mysql_query($insert);
?>
<h1>Registered</h1>
<p>Thank you, you have registered - you may now login</a>.</p>

Registration Page 2

 <?php
}
else
{
?>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<table border="0">
<tr><td>Username:</td><td>
<input type="text" name="username" maxlength="60">
</td></tr>
<tr><td>Password:</td><td>
<input type="password" name="pass" maxlength="10">
</td></tr>
<tr><td>Confirm Password:</td><td>
<input type="password" name="pass2" maxlength="10">
</td></tr>
<tr><th colspan=2><input type="submit" name="submit"
value="Register"></th></tr> </table>
</form>
<?php
}
?>

The full code can be found on GitHub: https://github.com/Goatella/Simple-PHP-Login

If the form has not been submitted, they are shown the registration form, which collects the username and password.Basically what this does is check to see if the form has been submitted. If it has been submitted it checks to make sure that the data is all OK (passwords match, ​the username isn't in use) as documented in the code. If everything is OK it adds the user to the database, if not it returns the appropriate error.

The Login Page 1

 <?php
// Connects to your Database
mysql_connect("your.hostaddress.com", "username", "password") or die(mysql_error());
mysql_select_db("Database_Name") or die(mysql_error());
//Checks if there is a login cookie
if(isset($_COOKIE['ID_my_site']))
//if there is, it logs you in and directes you to the members page
{
$username = $_COOKIE['ID_my_site'];
$pass = $_COOKIE['Key_my_site'];
$check = mysql_query("SELECT * FROM users WHERE username = '$username'")or die(mysql_error());
while($info = mysql_fetch_array( $check ))
{
if ($pass != $info['password'])
{
}
else
{
header("Location: members.php");
}
}
}
//if the login form is submitted
if (isset($_POST['submit'])) { // if form has been submitted
// makes sure they filled it in
if(!$_POST['username'] | !$_POST['pass']) {
die('You did not fill in a required field.');
}
// checks it against the database
if (!get_magic_quotes_gpc()) {
$_POST['email'] = addslashes($_POST['email']);
}
$check = mysql_query("SELECT * FROM users WHERE username = '".$_POST['username']."'")or die(mysql_error());
//Gives error if user dosen't exist
$check2 = mysql_num_rows($check);
if ($check2 == 0) {
die('That user does not exist in our database. <a href=add.php>Click Here to Register</a>');
}
while($info = mysql_fetch_array( $check ))
{
$_POST['pass'] = stripslashes($_POST['pass']);
$info['password'] = stripslashes($info['password']);
$_POST['pass'] = md5($_POST['pass']);
//gives error if the password is wrong
if ($_POST['pass'] != $info['password']) {
die('Incorrect password, please try again.');
}

The Login Page 2

 else
{
// if login is ok then we add a cookie
$_POST['username'] = stripslashes($_POST['username']);
$hour = time() + 3600;
setcookie(ID_my_site, $_POST['username'], $hour);
setcookie(Key_my_site, $_POST['pass'], $hour);
//then redirect them to the members area
header("Location: members.php");
}
}
}
else
{
// if they are not logged in
?>
<form action="<?php echo $_SERVER['PHP_SELF']?>" method="post">
<table border="0">
<tr><td colspan=2><h1>Login</h1></td></tr>
<tr><td>Username:</td><td>
<input type="text" name="username" maxlength="40">
</td></tr>
<tr><td>Password:</td><td>
<input type="password" name="pass" maxlength="50">
</td></tr>
<tr><td colspan="2" align="right">
<input type="submit" name="submit" value="Login">
</td></tr>
</table>
</form>
<?php
}
?>

This script first checks to see if the login information is contained in a cookie on the user's computer. If it is, it tries to log them in. If this is successful they are redirected to the members' area.​

If there is no cookie, it allows them to log in. If the form has been submitted, it checks it against the database and if it was successful sets a cookie and takes them to the members' area. If it has not been submitted, it shows them the login form.

Members Area

 <?php
// Connects to your Database
mysql_connect("your.hostaddress.com", "username", "password") or die(mysql_error());
mysql_select_db("Database_Name") or die(mysql_error());
//checks cookies to make sure they are logged in
if(isset($_COOKIE['ID_my_site']))
{
$username = $_COOKIE['ID_my_site'];
$pass = $_COOKIE['Key_my_site'];
$check = mysql_query("SELECT * FROM users WHERE username = '$username'")or die(mysql_error());
while($info = mysql_fetch_array( $check ))
{
//if the cookie has the wrong password, they are taken to the login page
if ($pass != $info['password'])
{ header("Location: login.php");
}
//otherwise they are shown the admin area
else
{
echo "Admin Area<p>";
echo "Your Content<p>";
echo "<a href=logout.php>Logout</a>";
}
}
}
else
//if the cookie does not exist, they are taken to the login screen
{
header("Location: login.php");
}
?>

This code checks our cookies to make sure the user is logged in, the same way the login page did. If they are logged in, they are shown the members area. If they are not logged in they are redirected to the login page.

Logout Page

 <?php
$past = time() - 100;
//this makes the time in the past to destroy the cookie
setcookie(ID_my_site, gone, $past);
setcookie(Key_my_site, gone, $past);
header("Location: login.php");
?> 

All our logout page does is destroy the cookie, and then direct them back to the login page. We destroy the cookie by setting the expiration to some time in the past.