Thank you for the excellent post .

Can you please help me become capable of doing such analysis?

How were you able to make the simplified ERD and come up with the conclusions under it

I want to learn this and be good at it ...

Also , need to be good with joins and although I did read out several links with examples ...I still seem to find issues like when my brain cannot digest how an inner join would get more rows than the individual selects and so on.