> Is that possible ?
Yes. The way you overcome this problem is by sticking an app server in-between the applet and the database. The applet talks to the app server (i.e. web service) and the app server should then access the database.
If you control who has access to the applet (i.e. trusted parties) then you may consider accessing the database directly but it is still not recommended.
> of course you'd still have the same problem, as any
> one of your untrustworthy users could fake being your
> applet with his reverse engineered code and sneak his
> way in ;)
True, but it is much less of a security risk than allowing the user to access the database directly.
Of course you should also make sure your web service accesses the database as a user with the absolute minimum privileges needed. Other security checks you can put at this level depend on what your application is doing really (certainly your users should need to authenticate themselves).