public/plugin/hello_world/install.php
<?php
/* PHP code to install the plugin
* For example:
*
// To query something to the database
$table = Database::get_main_table(TABLE_MAIN_USER); // TABLE_MAIN_USER is a constant check the main/inc/database.constants.inc.php
$sql = "SELECT firstname, lastname FROM $table_users ";
$users = Database::query($sql);
You can also use the Chamilo classes
$users = UserManager::get_user_list();
*/