I'm currently retrieving data from a vehicle fleet (fuel used, distance traveled...) through the manufacturer API. For each set of data, there is the date when the metric has been mesured. I will retrieve the data everyday through a rcon call and store it in my DB. The purpose is to keep the history for each vehicle so that I could get every metrics mesured for a vehicle between X date and X date later on.
I first thought of this :
But it doesn't seem right because of the "1,1" cardinality, so i transformed the 3 way relationship into 2 normal relationship :
At this point i wondered wether i could not simply store the field date in the metric entity (because I noticed the API would give me a datetime, so it's very unlikely that two metrics will be mesured at the same time):
And finally, i was wondering if putting everything in a data entity would not even be easier (but it feels kinda wrong):
So i'm completely lost as to what would be the best way to do this. Could someone tell me which way is the best or even if there is a better way and why ?