SQLSteven

I am trying to create a registration form (I have not stopped any SQL injecting, just trying to figure out why it's not working), but it's not inserting the table. Any ideas as to what I did wrong? <php $con = mysql_connect("localhost","thedatabase","secretpassword"); mysql_select_db('databasename'); $firstname = $_POST['firstname']; $lastname = $_POST['lastname']; $password = $_POST['password']; $email = $_POST['email']; for ($counter = 0; $counter < 17; $counter++) { $digit = rand(0, 61); $salt = $salt . substr("abcdefghijklmnopqrstuvwxyz1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ", $digit, 1); } $sql = "INSERT INTO clients (email, firstname, lastname, password, salt) VALUES ('$email', '$firstname', '$lastname', '$password', '$salt')"; mysql_query($sql); mysql_close($con); ?>