Warning: Undefined variable $conn in /htdocs/projet_detail.php on line 6

Fatal error: Uncaught TypeError: mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given in /htdocs/projet_detail.php:6 Stack trace: #0 /htdocs/projet_detail.php(6): mysqli_query(NULL, '\r\nSELECT p.*, c...') #1 {main} thrown in /htdocs/projet_detail.php on line 6