Native客户端应用程序必须访问mysql服务器端DB

I have a website with a mysql DB and I'm going to create a native app (probably in C#/WPF) which must access this DB.

Is it more secure and efficient to directly access this DB (and so keep the access information in the client app) or to create a PHP API ?

Thank you, Sébastien

Create a PHP API. If you connected directly, people could gain direct access to your mysql basically giving them full power.