Warning: Undefined variable $link in /var/www/html/base_dbid_meta.php on line 10

Fatal error: Uncaught TypeError: mysqli_real_escape_string(): Argument #1 ($mysql) must be of type mysqli, null given in /var/www/html/base_dbid_meta.php:10 Stack trace: #0 /var/www/html/base_dbid_meta.php(10): mysqli_real_escape_string() #1 /var/www/html/index.php(77): require('...') #2 {main} thrown in /var/www/html/base_dbid_meta.php on line 10