many to many relationships in Drupal

Hi,

I'm making a site that's going to have a many-to-many relationship, and was wondering if anyone else had thoughts on how to implement this - both in terms of the database, and about how to input it.

What do I mean?

I'm using CCK to have node references in my node edit pages - so I have one node type of 'organisation' and another of 'project' - and so I can select multiple projects in any organisation I'm editing.

Which is great: but what I need is, for each project added, extra fields that relate to that project's connection to the organisation. I.e. When i add a project to an organisation, I need more fields to appear - in my case, I need "amount this organisation gives to this project" (in either a negative or positive amount to indicate giving or receiving funds from it.)

In relational database terms, this is a many-to-many relationship - one organisation can be involved in many projects / one project can involve many organisations - which relational databases can't do directly. I need to create a third 'linker' table, I think. An illustrative example (from my database textbook!) would be if you have 'students' and 'courses' -

• one student can be enrolled on zero or many courses
• one course can contain many students

So that's solved by making a third category - registration.

For registration, it's 'each registration involves one student and one course'.

So - anyone done anything like this? I think what I'll probably do is create a linker table, and then just shoe-horn in some code to write to it. But any other suggestions - including if there's ways of hiding the extra linker fields until I fill in a 'project' field, or how best to shoehorn in the code - would be gratefully received.

Cheers me deerz,

Dan