Fatal error: Uncaught TypeError: mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given in /volume1/web/et/class/database/DB.php:28
Stack trace:
#0 /volume1/web/et/class/database/DB.php(28): mysqli_query(NULL, 'select a.nid,a....')
#1 /volume1/web/jendo/communicationBook/checkName.php(10): DB::queryF('select a.nid,a....')
#2 {main}
  thrown in /volume1/web/et/class/database/DB.php on line 28