Home Forums Article Discussions Article Discussions by Author Discuss Content Posted by Jeff Moden Displaying Sorted Hierarchies (SQL Spackle) RE: Displaying Sorted Hierarchies (SQL Spackle)

  • March 10, 2011 at 7:14 am

    #1297082

    Wesley Brown (3/10/2011)

    I prefer to use a two column approach to build a tree instead of the single column style that you have to split, it doesn't scale well. For smaller stuff like this HR representation it should be OK. Trees and Hierarchies in SQL from Joe Celko is one of my all time favorite books! Good article!

    your brother,

    Phil McCrevice

    If, by "two column approach", you mean "Nested Sets", I absolutely agree. This article was meant just to get folks that don't want to or can't convert to "Nested Sets" out of the woods for hierarchy structural sorting as has been asked in a very large number of posts here on SSC.

    In the larger article I'm writing on hierarchies, I'll actually demonstrate a new method for converting an "Adjaceny List" to a "Nested Set" that I think you'll like especially since it gets away from the RBAR of a "push stack" to build the "Nested Set". Ben-Gan also has an alternate method for doing the same thing.

    You'll also like the "warehouse" table that I'll build in the coming article which you might prefer to a "Nested Set" because the "warehouse" table contains preaggregated answers for the 4 of the more common hierarchical lookups that people seem to do on a regular basis.

    --Jeff Moden

    RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
    First step towards the paradigm shift of writing Set Based code:
    ________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.

    Change is inevitable... Change for the better is not.

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