One way I have done it in the past is using coded strings.... used it for threaded discussions... so you have say a 3 character key... top level is 
AAA 
AAB
...
000

[download]
children of AAA are 
AAAAAA
AAAAAB
...
AAA000

[download]
etc... it limits how wide you can go and how deep, but it works well for querying...

                - Ant
                - Some of my best work - (1 2 3)

In reply to Re: Trees in SQL, adjacency lists and sorting. by suaveant
in thread Trees in SQL, adjacency lists and sorting. by BUU

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