Warning: Undefined variable $connect in /var/www/html/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 /var/www/html/iteach4u/htdocs/2017/bullets/action/_like_ok.php:13
Stack trace:
#0 /var/www/html/iteach4u/htdocs/2017/bullets/action/_like_ok.php(13): mysqli_query(NULL, 'select no from ...')
#1 {main}
  thrown in /var/www/html/iteach4u/htdocs/2017/bullets/action/_like_ok.php on line 13