I've long recommended this book: "The Data Model Resource Book": https://amzn.to/2tXNiuF https://amzn.to/2tXNiuF You can look at an implementation of a number

I've long recommended this book: "The Data Model Resource Book": https://amzn.to/2tXNiuF https://amzn.to/2tXNiuF You can look at an implementation of a number of the ideas here: https://ofbiz.apache.org/ https://ofbiz.apache.org/ It's kind of complicated - probably overly so for some things - but there are a lot of ideas to think about and maybe utilize at least in part.