Fatal error: Uncaught TypeError: mysqli_num_rows(): Argument #1 ($result) must be of type mysqli_result, bool given in /htdocs/heat.php:8 Stack trace: #0 /htdocs/heat.php(8): mysqli_num_rows(false) #1 /htdocs/booking.php(36): include('/htdocs/heat.ph...') #2 {main} thrown in /htdocs/heat.php on line 8