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Editorial Team
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Asked: 2026-05-12T05:21:39+00:00

I’m having some trouble doing a tree-like query (what do we call this?) in

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I’m having some trouble doing a “tree-like” query (what do we call this?) in SQL.

Take a look at my diagram below (table and column names are in danish – sorry about that):

DB diagram http://img197.imageshack.us/img197/8721/44060572.jpg
Using MSSQL Server 2005, the goal is to find the most parent group (Gruppe), for each customer (Kunde).

Each group can have many parent groups and many child groups.

And, I would also like to know how to display the tree like this:

Customer 1
   - Parent group 1
      - Child group 1
         - ChildChild group n
      - Child group n
   - Parent group n
      - ...
         - ...
Customer n
   - ...

Another question:

How does the query look to get ALL the groups for all the customers? Parent and child groups.

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1 Answer

  1. Editorial Team

    I just can’t say it better than Joe Celko. The problem is usually that the models built doesn’t lend themselves well to build hierarchies, and that those models have to take in consideration the characteristics of your hierarchy. Is it too deep? Is it too wide? Is it narrow and shallow?

    One key to success on wide and shallow trees is to have the full path in the hierarchy in a column, like Celko mentions in the first link.

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