Nested sets, BOM, with many roots?

Been poking around all this. I veer from adjacency lists to nested sets. Nested sets look a lot more amenable to SQL. The only way I can get the adjacency lists to do some of the things I want will be by constructing SQL in code (I think). But nested sets always seem to end up at one root. Whereas I want multiple roots. Elton John world tour contains this which contains that etc. etc. Berlin Philharmonic world tour contains this which contains that etc. etc. There, hopefully, won't be any cross contamination (!), i.e. a child will only have one parent, but I seem to have 2 root nodes there. Or else are the both held under one root which is 'the business'. In which case things like number-of-levels queries will always be one off.

TIA, Mike MacSween Received on Sat Jan 03 2004 - 13:17:24 CET