Sure: http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/ http://mikehillyer.com/articles/managing-hierarchical-data-i... Joe Celko popularise

Sure: http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/ http://mikehillyer.com/articles/managing-hierarchical-data-i... Joe Celko popularised them. I've been unable to find when they were first introduced; but a search of my source code archive points to having written one ~14 years ago.