Warning: Undefined variable $link in /volume1/homes/Dušánek/www/elateridae.com/manfred.php on line 7

Fatal error: Uncaught TypeError: mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given in /volume1/homes/Dušánek/www/elateridae.com/manfred.php:7
Stack trace:
#0 /volume1/homes/Dušánek/www/elateridae.com/manfred.php(7): mysqli_query(NULL, 'SELECT id, subf...')
#1 {main}
  thrown in /volume1/homes/Dušánek/www/elateridae.com/manfred.php on line 7