Apps programmieren Wallis

Apps programmieren:
Fatal error: Uncaught Error: Call to undefined function mysql_select_db() in /home/httpd/vhosts/wenpas.com/httpdocs/www.netzwerkhilfe.ch/index.php:56 Stack trace: #0 {main} thrown in /home/httpd/vhosts/wenpas.com/httpdocs/www.netzwerkhilfe.ch/index.php on line 56