Just bookmarking a few things here.
- The “base” reference to understand hierarchical sets vs nested sets
- A few practical examples ; there is a part 2 and a GitHub
- A neat query to convert a traditional hierarchy (with a parent id) to a nested set ; found from this post which unfortunately uses the HierarchyID of SQL2008
- Speaking of which, there is a HierarchyID data type in SQL2008. Neat, but makes it (even) harder to switch to another DB.