Can there be in whatever way will be able to connect with a server DB (Oracle, MS SQL, Sybase, ...) from the Home windows Mobile application (designed in C# using Versus 2008). Can there be support for say ODBC or any other technologie? I am hooking up to some LAN via WLAN or via UMTS.

There's no possibility that i can install one more server component.

Sure System.Data.SqlClient for SQL Server works all right. For Oracle there's OraDirect.

It appears that no. OdbcConnection members aren't marked with Compact Framework support flag

Take a look at SQL Server Compact: it shares a typical API using the other Microsoft SQL Server models. Additionally, it includes ADO.Internet companies for data access using ADO.Internet APIs, and built-in synchronization abilities (from WikiPedia)

No, the only real direct connectivity option in CE is System.Data.SqlClient, which only works best for SQL Server.

I have only tried it utilizing a purpose-built socket server - that has the advantage of helping you to transform it into a helpful abstraction layer, but is really a medium-sized little bit of work. Portable to the tcpip networkable client device, however. You may also make it asynchronous that is almost needed inside a mobile atmosphere.