Simple login using php (part 2)

First i will make a login form.

<form method="POST" action="login.php">

Username: <input type="text" name="userid" >

Password: <input type="password" name="password" >

<input type="submit" value="login" name="login">

</form>

Now lets have a look at login.php

<?PHP

//isset function checks for exsistence of the variable if isset returns false then it redirects to login page

if (!isset($userid) || !isset($password)) {

header( "Location: http" address of your login page " );

}

//here it checks if forms fields are submitted empty or not

//if empty it redirects to login page

elseif (empty($userid) || empty($password)) {

header( Location:"address of login page" );

}

else{

//addslashes() function is used to escape double quotes ("), single quotes ('), backslash (\) or NULL.It does so by automatically inserting a backslash (\) character in front of the characters in a string.

//addslashes() function is especially useful to use on a string before inserting into a database

$user = addslashes($_POST['userid']);

$pass = $_POST['password'];

//Store the form value into php variables

$dbHost = "localhost";

$dbUser = "Database userid";

$dbPass = "Database password ";

//as assumed earlies we have a login database

$dbDatabase = "login";

//conneting to the database

$db = mysql_connect("$dbHost", "$dbUser", "$dbPass") or die ("Error while connecting to database.");

mysql_select_db("$dbDatabase", $db) or die ("Couldn't select the database.");

$result=mysql_query("select * from users where username='$userid' AND password='$password'", $db);

//checks if result is not empty

$row = mysql_num_rows($result);

if($row > 0)

{

while($row = mysql_fetch_array($result))

{

//A session is started and variable registered

session_start();

session_register('userid');

//the session variable userid is used through out the users session

echo 'Successful login !';

//redirect to a page

//let check.php be the page where you want to redirect

header( "Location: http:"check.php");

}

}

else {

echo 'There was an error logging in please try again.';

}

?>

Please check the next post where i will discuss about how to check if user is logged in.