This book provides a great overview on graphs, trees, and hierarchies, and then several great examples of how to work with them in a Relational Database enviroment. A particular strength of the book is that it balances being a "Cookbook", providing useful code snippets to work with the structures, but also explaining the how and why of each of the snippets.
I am looking forward to using many of the methods in ongoing projects; as well as looking forward to researching some of the other topics (petri nets, state transition graphs) further.
While I just scanned it for a project at work. I was very impressed with the structure and presentation. Very easy to understand and presented the material excellently.