Fatal error: Uncaught Error: Call to a member function prepare() on null in /users/y/x/yxue/bin/Database.php:404
Stack trace:
#0 /users/y/x/yxue/www-root/cs148/dev-lab5/index.php(27): Database->select()
#1 {main}
thrown in /users/y/x/yxue/bin/Database.php on line 404