Hello, > The only difference is that you have moved parent outside main table. > No benefits at all. You have to create two records I two tables instead of > one. You have to make joins to see what is the parent of particular child. > I am strongly against this.
Why? 1) relational theory clearly states you should store what is TRUE (this means: no NULLs). Obviously, people are used to NULLs, but this doesn't make them right. 2) there's nothing wrong with joins 3) there's nothing wrong with multiple inserts 4) you avoid self-joins, which can be tedious to write. With regards, Martijn Tonies Database Workbench - developer tool for InterBase, Firebird, MySQL & MS SQL Server. Upscene Productions http://www.upscene.com > > It's really clear what you want. Please specify. > > > > If what you basicaly want is just a tree structure, then it's done like > that: > > > > > > CREATE TABLE something ( > > id INT AUTO_INCREMENT PRIMARY KEY NOT NULL, > > parent INT NOT NULL, > > data1 CHAR(255), > > data2 CHAR(255), > > ... > > > > ); > > > > Then you can specify the parent node id for each record in database. > > This is how tree-like structures are stored in SQL. Hope that helps. > > That is ONE way to store a tree structure :-) > > Another would be: > > ITEMS > (ItemID INT AUTO_INCREMENT PRIMARY KEY NOT NULL, > other stuff) > > ITEM_PARENT > (ItemID int, > ParentID int > primary key (ItemID, ParentID) > ) > > > I prefer the latter. -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
