Data model with canonical date

[Anonymous]

Hello,

I have some issues to find an appropriate data model and I would like to have some advise if it is possible.

I would like to compare two files with multiple references of products, a new and an old one.

So I have the following table :

ID	New Station	New beginning date	New Version	New finished date	Old Station	Old beginning date	Old Version	Old finished date

The issue is that I have to draw a graph with dates so I created a canonical table

ID	New Station	Old Station	Beginning date	data type
				Old or New

But then I need the same thing with the finished date. I would need a canonical table with the beginning date and the finished date but I don't know how to do that without having two different table...

I don't think my data model is the best one and I would like to have some advise because my loading is quite long right now with the canonical table.

Thanks for your time

Best regards,