mysql - Many-to-many and hierarchical database design

Question

i'm designing a database and run into some problems:

I have a Document entity consisting of many fields. Mostly i want to use the same version of that document but sometimes users should be able to customize some of the fields for a specific usage of the document. Not customized fields should use the value of the parent document as a default. Changes to the parent document should get propagated to any not customized field of a specific usage.

I have a table Document:

Document:
id | field1| field2 | field3|  parentDocumentId

For parent documents is parentDocumentId = Null. Customized usages of a document have the new value for the customized fields saved and for not customized fields simply null.

1. Is this a good design?

2. Furthermore the Document entity has a many-To-many relationship with another entity Course. My problem now is when i look at a row of Document with parentDocumentId != null and courses = null i can't determine if the relationship is either not customized by the user yet and i should use the value of the parent document or the field is customized by the user and simply has no courses. How can i solve that?

Thanks

question from:https://stackoverflow.com/questions/65649221/many-to-many-and-hierarchical-database-design

Answer 1

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