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Design Patterns of Data Bases - Coggle Diagram
Design Patterns of Data Bases
Graph, Trees and Hierarchies Overview
branch of mathematics that deals with abstract structures
graphs that have the following properties
Every node is the root of a subtree.
A tree is a connected graph that has one less edge than it has nodes
A tree is a connected graph that has no cycles
hierarchy is a directed tree with extra properties: subordination and inheritance
Adjacency List Model
there has to be one column for the identifier and one column of the same data type
The single table works best for organizational
Nested Sets Model
was overlooked for so long among SQL programmers
removing is a costly procedure too because of recalculating of borders and ID;
selection is the purpose of this model
Materialized Path
stores the path from the root to each node as a string at that node
alter the root of the tree
selection is the strength of this pattern
removal of item doesn’t involve violations of the tree integrity
adding and editing are more difficult than in the adjacency list pattern