Relational databases are not well suited for representing and processing hierarchical data. Clever schemes are required to represent trees in the flat format of the relational model, as well as answering queries such as retrieving all nodes in a sub-tree, all nodes at a particular level and the nodes on the path from a node to one of its descendants. Some areas where hierarchical data needs to be stored and processed include XML data warehousing, organization chart in automation systems, bioinformatics and pyramidal games that require hierarchical data representation. In this book, a new...