Warning: mysql_num_rows() expects parameter 1 to be resource, boolean given in /home/folder/public_html/folder/folder/login.php on line 18 [duplicate]

Answer 1

Warning: mysql_ finctions are deprecated as of PHP 5.5.0, and will be removed in the future. Instead, the MySQLi or PDO_MySQL extension should be used.

You are not checking if the mysql_query was successful or not. If the query was unsuccessful mysql_query returns false. Refer to mysql_query Manual

Try

$result=mysql_query($sql);
if ($result==false)
{
    die(mysql_error());
}
$count=mysql_num_rows($result);