Autonumber and one-to-many relationship

Your design seems reasonable to me. While you do have to update all subsequent records when new processes are added or deleted that is easy to accomplish. You just issue an update like:

UPDATE ProcessOrder
SET ProcessOrder = ProcessOrder+1
WHERE ProcessOrder >= [step# where you want to insert]

and then do your insert or delete.

The only other way I can think of would be to design the schema to store the next process id on the row. Something like:

ProcessID | ParentProcessID | NextId
--------------------------------------------------
UUID2     | UUID1           | UUID3
UUID3     | UUID1           | UUID4
UUID4     | UUID1           | NULL

Then if you insert a new step - say between UUID3 and UUID4, you perform more of a linked list operation which will update UUID3|UUID1's NextId to UUID5 and then just insert the new UUID5 with a NextId of UUID4.

This will reduce the UPDATEs to 1 in most cases, but it will make querying the process more difficult as now you have to walk the list from top to bottom to list out step by step.

You need to decide which process you want to favor - inserting and updating or retrieving. If you favor retrieval (which you might if changes are infrequent and reporting is frequent, and the lists are short), then go with your original design. If you favor insert and update (which you might if changes are happening all the time and reporting is infrequent, or lists are really really long), then go with the linked list approach.

I hope this helps. Interested in what other solutions the community might come up with as I'd love to broaden my knowledge around this!

Based on your diagram above what you have is a one to many, not a many to many relationship. You have your Researcher table and your Stay table. If you add the researcher id in the stay table to the primary key you have a relationship of:

Researcher.ResearcherId -> Stay.ResearcherId

Where a given researcher can have multiple stays. For example

Researcher John Smith has an Id of 2.

In the stay table you would have

From       Till       ResearcherId
1/1/2013   1/5/2013   2
2/6/2013   3/1/2013   2

etc