http://dev.mysql.com/tech-resources/articles/hierarchical-data.htmlByMikeHillyerIntroductionMostusersatonetimeoranotherhavedealtwithhierarchicaldatainaSQLdatabaseandnodoubtlearnedthatthemanagementofhierarchicaldataisnotwhatarelationaldatabaseisintendedfor.Thetablesofarelationaldatabasearenothierarch...