Warning: Undefined variable $conn in C:\xampp\htdocs\hr_\index.php on line 37

Fatal error: Uncaught TypeError: sqlsrv_query(): Argument #1 ($conn) must be of type resource, null given in C:\xampp\htdocs\hr_\index.php:37 Stack trace: #0 C:\xampp\htdocs\hr_\index.php(37): sqlsrv_query(NULL, 'SELECT [Positio...', Array, Array) #1 {main} thrown in C:\xampp\htdocs\hr_\index.php on line 37