How to implement the notion of assets in PostgreSQL?

Question

I am currently building a database for different sensors and now i have to create assets. By asset, i mean group of sensors like in a room or a group of sensors of the same type.

The thing is : 1 sensor can be in Asset A (Machine 1) and Asset B (Machine 2). We can consider it to be a temperature sensor in a room containing the 2 machines.

What i want to do, is to link that sensor to the 2 assets and i don't really see how to do it and this is where i need some help.

In my database, i can give an Asset_ID, and going in the Asset_Table, i can link my sensor to ONE machine using the Asset_ID.

So, how can i link the sensor to 2 Asset_ID, so it will be associated with the 2 machines in my database

I hope this is a bit clear !

• Dave

Answer 1

You want an AssetMachines table:

create table AssetMachines (
    AssetMachine_Id serial primary key,
    Asset_Id int references assets(asset_id),
    Machine_Id int references machines(machine_id),
    . . .  -- more columns can go here
);

Answer 2

I think the many-to-many relationship is best expressed by

CREATE TABLE assetmachines (
    asset_id integer references assets (asset_id),
    machine_id integer references machines (machine_id),
    PRIMARY KEY (asset_id, machine_id)
);