数据库表关系设计

Question

I am trying to write out a database design to include the following relationships, I have tried to work them out from the top down, hierarchically, but the relationships seem to be better connected another way, I just cannot see, or express how.

(This comes from a FOUO system from work, so the names have been changed to reflect that classification, that's why the names may look odd.)

Each Branch 1:n Functional Areas ,

Each Building 1:n Groups ,

Each Group 1:n Units ,

Each FunctionalArea 1:n Checklists ,

Each Checklist 1:n Items , and

Each Unit 1:n Checklists and

This was solved by re-evaluating the relationships without concern for the size or data type they would hold. 1:n relationships were used in lieu of n:n.

Answer 1

one simple way I've used that would handle this is to have tables for each pairing: branch-function, building-function, building-group, group-unit, unit-checklist, checklist-item, keeping the objects and relationships separate.

It's basically tuple soup, but keeping that sorted is what a relational db is good at. Accesses will be doing primary-key joins on multiple tables. How large do you expect your dataset to grow?

The limits (100 checklists, etc) are policy. Design the schema for simplicity and performance, implement policy in the application layer.

Answer 2

When you are designing a database you need to be specific about the relationships. For example you need to mention things like "A functional area can only belongs to a one branch only". These will help to determine either we are going to have 1:1 relations or 1:n or something else.

However i have come up with an answer.