Re: Organisational question: surely someone has implemented many Boolean values (tags) and a solution exist

On 20 January 2011 16:20, Dotan Cohen <dotancohen@gmail.com> wrote: > On Thu, Jan 20, 2011 at 17:00, Richard Quadling <rquadling@gmail.com> wrote: >> I'd have my items table, my tags table and a join table for the two. >> My join table is really simple. UniqueID, ItemID, TagID. >> > > Yes, that is the first approach that I mentioned. It looks to be a > good compromise. > > >> I'd recommend using a nested set approach for the tags >> (http://dev.mysql.com/tech-resources/articles/hierarchical-data.html >> gives a good explanation on the issues and methodology of nested >> sets). >> > > That is terrific, at least the first half. The second half, with the > Venn diagrams, is awkward! > > -- > Dotan Cohen > > http://gibberish.co.il > http://what-is-what.com > When you get heavily nested data, the adjacent set model (where you have a parentid for every uniqueid), you very quickly get into complicated logic trying to traverse n-levels. The nested set model is specifically built to handle this issue. I'd recommend getting to grips with it. It will make finding items belonging to a group (or a super group) a LOT easier. Especially if you have multiple tag hierarchies. -- Richard Quadling Twitter : EE : Zend @RQuadling : e-e.com/M_248814.html : bit.ly/9O8vFY