December 2014
Intermediate to advanced
852 pages
17h 57m
English
Content preview from Joe Celko's SQL for Smarties, 5th Edition
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Chapter 28
Trees and Hierarchies in SQL
Abstract
A tree is a special kind of directed graph. A hierarchy is a special kind of tree. IMS and other early databases, operating systems, and file systems are based on this model. It can be modeled with SQL.
Keywords
n-Ary tree
Subtrees
Leaf node
Root node
Adjacency list model
Nested sets model
Subordinates
Path
Parts explosion
A tree is a special kind of directed graph. Graphs are data structures that are made up of nodes (usually shown as boxes) connected by edges (usually shown as lines with arrowheads). Each edge represents a one-way relationship between the two nodes it connects. In an organizational chart, the nodes are employees and each edge is the “reports to” relationship. In a parts ...
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