From: "Gabriel Richards" Newsgroups: comp.databases.theory Subject: Creating a Hierarchical Structure Lines: 33 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 X-MIMEOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Message-ID: Date: Wed, 08 Aug 2001 16:49:25 GMT NNTP-Posting-Host: 66.27.200.200 X-Complaints-To: abuse@rr.com X-Trace: typhoon.we.rr.com 997289365 66.27.200.200 (Wed, 08 Aug 2001 09:49:25 PDT) NNTP-Posting-Date: Wed, 08 Aug 2001 09:49:25 PDT Organization: Road Runner How would you, or what is the commonly accepted way, of creating a database which represents a hierarchical category structure ala Yahoo!? What I have done until now is to create a table called categories. Each field has a categoryID, a parentID and the category's name. The parentID is "0" for all top level categories, and all sub-categories inherit a parentID containing the categoryID of the category above it. So for instance: CategoryID ParentID Name 1 0 Shopping 2 1 Retail 3 1 Business to Business 4 2 Clothing I was talking to some guy yesterday who said the standard what of creating such a system in a directory was to have a table which contains your root categories and then a new table for every level of sub-category. So if your directory goes 10 levels deep you have 10 category tables each containing the categories of a level. What's better and why? What do you guys do? Gabe -- Ender Technology Web Applications, Design, Hosting http://www.endertechnology.com 310-516-7411