Tell me where to dig on the client-server application

Question

PostgreSQL

I don’t know where to start studying the issue, I would like to find key words, examples. Actually the situation itself.
There is an application on WPF. There is an external database on PostgreSQL. The application is something like an admin panel, connecting to the database by IP / login / password from the database, works through the entity framework. It was necessary to expand the program so that clients could work with the program themselves: introduce personification, that is, add program users, separate their rights and access to data. Therefore, a mess formed in my head:
1. Are there any best practices for designing tables for multi-user applications?
2. What do I need to know/read about authentication?
3. Is there a need for a server as a layer between the user and the database? Or is it all decided by the database architecture and its internal functions?

Answer 1

Found a great article in two parts WCF Client Server Application with Custom Authentication, Authorization, Encryption and Compression . Basically just what I need. Hosting only for the server you need to find :/

Answer 2

google -> uac c#

Answer 3

Well, prescribing a login / password from the database to the client is not a very good option, they will disassemble and do things in your database. It is better to make a layer in the form of a server.
I would look towards a new thing from MS since you write in C # - ASP.NET MVC4 WebAPI. This is such a thing to build RestFul api.
Actually, if you already have models and you have already mapped them using the Entity Framework, you just have to transfer them to a new project with ASP.net mvc, write controllers that will receive / send responses to your WPF application. And in WPF, instead of methods that pull the database (by the way, they can be transferred to the server), replace them with methods that will pull your API.
Here is an article for you, where they write the server part from scratch .
If I understand your question correctly.