Warning: Undefined variable $connect in /volume1/web/iteach4u/htdocs/2017/bullets/action/_like_ok.php on line 13

Fatal error: Uncaught TypeError: mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given in /volume1/web/iteach4u/htdocs/2017/bullets/action/_like_ok.php:13
Stack trace:
#0 /volume1/web/iteach4u/htdocs/2017/bullets/action/_like_ok.php(13): mysqli_query(NULL, 'select no from ...')
#1 {main}
  thrown in /volume1/web/iteach4u/htdocs/2017/bullets/action/_like_ok.php on line 13