PHP Cryptography, Storing Passwords

Storing cleartext password in database is the worst idea, instead, you should store the hash of the password and use a salt for even best results.

<?php
 /*$password contains the password*/
 $salt = 'SHIFTLEFT';
 $passwordHash = md5($salt.md5($password.$salt));
 
 /* insert the $passwordHash to database */
?>

And to check whether user input the correct password, hash the provided password using the same technique, and compare them.

<?php
 $userPass = $_POST['password'];
 $salt = 'SHIFTLEFT';
 $passwordHash = md5($salt.md5($userPass).$salt);

 /*compare $passwordHash with password stored in database*/

?>

Hope it helps.