Password Reset

[NLT]

<?php
include('global.php');
//This code runs if the form has been submitted
if (isset($_POST['submit'])) 
{

// check for valid email address
$email = $_POST['remail'];
$pattern = '/^[^@]+@[^\s\r\n\'";,@%]+$/';
if (!preg_match($pattern, trim($email))) {
  $error[] = 'Please enter a valid email address';
} 

// checks if the username is in use
$check = mysql_query("SELECT mail FROM users WHERE mail = '$email'")or die(mysql_error());
$check2 = mysql_num_rows($check);

//if the name exists it gives an error
if ($check2 == 0) {
$error[] = 'Sorry, we cannot find your account details please try another email address.';
}

// if no errors then carry on
if (!$error) {

$query = mysql_query("SELECT username FROM users WHERE email = '$email' ")or die (mysql_error());
$r = mysql_fetch_object($query);

//create a new random password

$password = substr(md5(uniqid(rand(),1)),3,10);
$pass = md5($password); //encrypted version for database entry

//send email
$to = "$email";
$subject = "Account Details Recovery";
$body = "Hi $r->username, \n\n you or someone else have requested your account details. \n\n Here is your account information please keep this as you may need this at a later stage. \n\nYour username is $r->username \n\n your password is $password \n\n Your password has been reset please login and change your password to something more rememberable.\n\n Regards Site Admin";
$additionalheaders = "From: <user@domain.com>\r\n";
$additionalheaders .= "Reply-To: noprely@domain.com";
mail($to, $subject, $body, $additionalheaders);

//update database
$sql = mysql_query("UPDATE users SET password='$pass' WHERE email = '$email'")or die (mysql_error());
$rsent = true;


}// close errors
}// close if form sent

//show any errors
if (!empty($error))
{
	$i = 0;
	while ($i < count($error)){
	echo "<div class=\"msg-error\">".$error[$i]."</div>";
	$i ++;}
}// close if empty errors


if ($rsent == true){
echo "<p>You have been sent an email with your account details to $email</p>\n";
} else {
echo "<p>Please enter your e-mail address. You will receive a new password via e-mail.</p>\n";
}

?>

<form action="" method="post">
<p>Email Address: <input type="text" name="remail" size="50" maxlength="255">
<input type="submit" name="submit" value="Get New Password"></p>
</form>

 

I know I need to replace my emails, but I need to select "mail" from the users table, and then username from the user table. From the code I've got, when I type in the email, I get an error

Unknown column 'email' in 'where clause'

 

I'm not sure whether it's connecting or not, what could I add to make it connect to the database?