NYCPHP Meetup

[Roland Cozzolino]

You can also use nested set theory.  This makes retrieval of parents, 
children, siblings, etc. extremely fast and efficient.  This also allows 
for an unlimited hierarchy.  The math is a bit more confusing at first, 
but quite trivial once you get it. The adjacency list model is 
significantly slower but much easier to understand.  A good link to help 
understand this is 
http://www.intelligententerprise.com/001020/celko.jhtml?_requestid=1266295.  
Also note, that in Oracle, there is a specific function to deal with 
this ... postgres, mysql, sql server and others do not deal with 
hierarchical structures in flat format.  Hope this helps, although I am 
not sure what the question was in the first place.

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