SQL表-此设计可接受/良好实践吗？

Question

I'm in the process of developing/designing a small system to keep track of servers, what applications run on these servers, and for each application what environments exists on the server. I have a quick question about good design patterns/practices.

I have 3 tables, one for each entity. They are (abbreviated) as follows:

Server
Id : int

Application
Id : int

Environment
Id : int

Now, my question is:

Would it be acceptable to create a joining table as such:

AppServerEnvironments
ServerId : int
ApplicationId : int
EnvironmentId : int

Or, is it better practice to create two joining tables as such:

ApplicationServer
ServerId : int
ApplicationId : int

ApplicationEnvironment
ApplicationId : int
EnvironmentId : int

I've tried going with the second option, but cannot seem to figure out a way to join all 3 tables properly.

Any input/guidance is greatly appreciated.

Thank you!

Answer 1

so you would have something like this:

application
-----------
application_id

server
-----------
server_id

application_instance
---------------------
application_id
instance_id
name <- name this one DEV, or PROD etc.
description <-  here describe the use of the DEV system

now say which one lives where...

server_instance
---------------
server_id
instance_id

Answer 2

It depends. If you require all three keys to be present in the joins, then you should go for the AppServerEnvironments solution. If the Server/Application pair does not require an Enviroment or the Application/Environment does not require a Server , then you'd best use the ApplicationServer/ApplicationEnvironment solution. This way, you can define composite primary keys on the tables without having NULL values.