static function get_connection()
{
$host = "localhost";
$user = "******";
$password = "******";
$base = "cash_statistic";
// if (empty(self::$connection)) {
self::$connection = new mysqli($host, $user, $password, $base);
if (self::$connection->connect_errno) {
echo "Failed to connect to MySQL: (" . self::$connection->connect_errno . ") " . self::$connection->connect_error;
}
// }
return self::$connection;
}