mysql_select_db() expects parameter 2 to be resource, object given

You are using both mysqli and mysql simply change

mysql_select_db()

With

mysqli_select_db

Reference http://php.net/manual/en/mysqli.select-db.php

updated

When you use mysql_select_db you are supposed to use mysql api and so you have to exatibilish connection to database with mysql sintax mysql_connect Reference

Mysql is now deprecated so it's correct either to use mysqli or PDO