ERD Diagram help!

[Richie27]

Hi,



I have four entities that I want to link up but am a little confused.

My entities are:

1. Cost Centre (Example fields would relate to the internal business, call it say Jabba Industries and all the others would relate to external parts of the business)
2. Categories (The categories would be like Bank, Payroll, Accounts etc and will apply to both internal and external parts of the business)
3. Files ( Files will be specific files that need to be stored, for example - the category payroll will include tax reports, payroll reports etc.)
4. Box (Boxes, in the case of the internal company will store specific files, however in the case of external companies all that needs to be stored is the category of files with no need to know what specific files there are. In other words - no need for entity 3 Files.

I currently have CostCentre(1) -----(M)> Category (1)-------(M)>Files


but am a little unsure how to bring the box into the equation. One box could have many categories in the case of external businesses or many files in the case of internal ones - but won't have both. Hmmm.............

[Robeen]

Hi Richie,
When you say 'entities' do you mean Tables?
Could you explain in different words what exactly you want to do?
For example, I don't understand what this is:

I currently have CostCentre(1) -----(M)> Category (1)-------(M)>Files

I'm sorry, but I am finding it difficult to understand exactly what outcome you need.

[Richie27]

Hey, thanks. I actually realised. What I needed to do, just after I typed that. Will post later. Internet down at the moment unfortunately. Just as I was making progress too!

[Richie27]

Well, I just related the category table to the box table in a one to many relationship. ........ I think maybe in future I will post a blank copy of my DBase to clarify things for you guys.......cheers.