How to represent a data tree in SQL?

Avi Harush picture Avi Harush · Feb 1, 2010 · Viewed 46.7k times · Source

I'm writing a data tree structure that is combined from a Tree and a TreeNode. Tree will contain the root and the top level actions on the data. I'm using a UI library to present the tree in a windows form where I can bind the tree to the TreeView.

I will need to save this tree and nodes in the DB. What will be the best way to save the tree and to get the following features:

  1. Intuitive implementation.
  2. Easy binding. Will be easy to move from the tree to the DB structure and back (if any)

I had 2 ideas. The first is to serialize the data into a one liner in a table. The second is to save in tables but then, when moving to data entities I will loose the row states on the table on changed nodes.

Any ideas?

Answer

Björn picture Björn · Nov 28, 2010

I've bookmarked this slidshare about SQL-Antipatterns, which discusses several alternatives: http://www.slideshare.net/billkarwin/sql-antipatterns-strike-back?src=embed

The recommendation from there is to use a Closure Table (it's explained in the slides).

Here is the summary (slide 77):

                  | Query Child | Query Subtree | Modify Tree | Ref. Integrity
Adjacency List    |    Easy     |     Hard      |    Easy     |      Yes
Path Enumeration  |    Easy     |     Easy      |    Hard     |      No
Nested Sets       |    Hard     |     Easy      |    Hard     |      No
Closure Table     |    Easy     |     Easy      |    Easy     |      Yes