Non email activated user warning

[bytesize]

I would like to include: 'You have not activated your account, please check your email' message if the user is registered but not activated. The database field 'active' is set to '0'. When the user activates their account from an e-mail, the 'active' field is set to '1'. This code works but I can't get it to display the not activated message which is not included because I didn't want to create confusion.

<?php	
function login($username, $password)
{
db_connect_posts();

$query = sprintf("SELECT * FROM users
WHERE 
 user_email = '%s' AND
 user_pwd = '%s' AND 
 active = '1'"
 , mysql_real_escape_string($username),
	 md5($password));

$result = mysql_query($query);

$number_of_posts = mysql_num_rows($result);
if($number_of_posts == 0)
{
return false;
}

$row = mysql_fetch_array($result);

$_SESSION['user'] = $row;

return true;							
}
?>

Login switch

<?php
case "login_user":
if(login($params['user']['user_email'], $params['user']['user_pwd']))
{
	redirect_to('posts');
}
else
{
	flash_warning('Username or password is invalid');
	$route['view'] = 'login';
}
break;
?>