({{index.php}} > {{   include_once}} [a1]) () ||
(a1:{{include/}}|{{config.inc.php}} > {{   include_once}} [a2]) () ||
((a2:{{include/core/}}|{{config.mysql.inc.php}})) - {{include_once}} () > ({{1) include/core/}}|{{mysql.inc.php}})
    

Legend:

config.mysql.inc.php -> MySQL config file

1. includes mysql class
2. make connection to the database
3. get configuration settings from the database and saves them in session