I'm developing a Visual Studio C# application, which is related to a database. It currently uses a database file (SQLite). But I want to connect it to an online database. The idea is: the same copy of database should be on users' computers (in SQLite files) and on a server. Every time a user logs in, his local database is synchronized with the one on the server. (The user gathers the data)

My question is, what kind of database and what kind of server should I choose?

The requirements are the following:
- it should be safe (the data is user's precious secret)
- the server should be possibly cheap (the "investor" is still a student)
- the database should be free or cheap, but still safe

I was thinking about Microsoft Azure or Amazon Web Services, but I didn't find much information about them. Is it a reasonable choice?


Why you need to store the data in the client machine in case of a online application ?

If you want something free try to go for oracle Express

Thanks for sharing the important information.