Best DataBase for mobile games

Hello ,
I want to make a Mobile MMO, but i practicaly don’t know much about storing data and security. I want to store on server all logins/passwords of users and some variables ( eg. gold) .

And there’s a question:

What data base is best for it? Well, you’ll probably tell me “that one that suits you best” , so additionaly : What is the simplest/fastest to learn?
And what about security, i know that client shouldn’t have acces to dataBase and there should be externall script which client will call to get the data. Same question as above.

I know only c# and c++ :<

I’ve read some positivie opinions about SQLite, but is it good for handling that staff?

Is the db going to run on the mobile device? If so, I’d definitely recommend SQLite. It’s small, fast, and doesn’t require any administration. Otherwise, if the db is going to reside on a server, you have lots of options. The choice likely depends on economics, feature set, and/or what may be available through your site’s hosting provider, assuming that’s how it’ll be accessed.

For running a SQLite database on your mobile device, I recomment reading this post.

I’ve chosen to use a PCL, because I have to deploy my apps to other platforms within a very short period of time. I wrote my findings here