Hi guys, I try to applied your solutions but I have problems whit it. I need to achieve this schema( -> is something like ../ it means that it is one level up folder): connec.php(class Connect MySql)-> select.php(class Select MySql) -> .... -> mysql.php(class MySQL include all classes, Connect...)-> .... -> ... -> -> db.php(class db include all classes, MySQL, Oracle..) connec.php(class Connect Oracle)-> select.php(class Select Oracle ) -> .... -> oracle .php(class Oracle include all classes, Connect...)-> .... -> ... -> download.php(class Download)-> unzip.php(class Unzip) -> .... -> files.php(class Files include all classes, Download...) -> file.php(class file include class Files) .... -> ... -> hash.php(class Hash)-> capcha.php(class Capcha) -> .... -> secure.php(class Secure include all classes, Hash...) -> security.php(class security include class Secure) .... -> ... -> *ect. ect. ect. ect. ect. ect. ect. ect. ect. ect. ect. ect. ect. ect. ect. * And in the end, in the same folder as db.php and security.php I will have file application.php which will contain class application and in its __construct() method I will make link classes db, security, file ect. ect. So I will just include file application.php make object from class application and then just do $object->db->connect()(of course if it will by MySql or other database will be stored in some config.php file). Thanks, Dominik