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Fatal error: Uncaught TypeError: mysqli_query(): Argument #1 ($mysql) must be of type mysqli, null given in /var/www/html/main/dayofappt.php:10 Stack trace: #0 /var/www/html/main/dayofappt.php(10): mysqli_query() #1 {main} thrown in /var/www/html/main/dayofappt.php on line 10