# drop all tables in the 5.3.x database
# copy all 5.2.x project's database tables to the 5.3.x project's database
# delete `system/config.php` file from the 5.3.x project
# copy `system/config.php` file from 5.2.x project to 5.3.x project
# confirm, that copied file contain 'mysql' among values of configuration variables and do not contain 'mysqli' there
# in the `system/config.php` file change value of $_CONFIG['Database']['DBName'] configuration variable from 5.2.x project's database name to 5.3.x project's database name
# in the `system/config.php` file change value of $_CONFIG['Misc']['WebsitePath'] configuration variable from 5.2.x project's base path to 5.3.x project's base path
# in the command-line run command `chmod 777 system/config.php`
# in the browser open `core/install.php` of 5.3.x project
# confirm that `system/config.php` file contains 'mysqli' in place of recent 'mysql' value