> The way I'd do it if I had to do it again: > Give each record a unique id, generated by the application. > Denote levels with extra letters. > > So: > > AA - Automotive transport > AAAA - Cars > AAAB - Motorcycles > > The structures has the added bonus of making it very easy to > determine all the > sub-categories of a category, no matter how deep the tree is > below the category > you're looking at. With the first approach it is not possible > to do this in a > single SQL query. You could do this with a function, I guess. The problem with this method is if you need to insert a category, or move a category. You'll need to re-id a bunch of categories, and bubble those changes out to every table that refers to this table. Stuart Statman Director of Software Development Slam Media, Inc.
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