Data Model

Data model is a way of organizing the logical structure of data storage in a database. There are three main types of data models which differ by the way of establishing links between the data.

  1. Hierarchical:
  2. the information is organized in accordance with the tree structure principle, in the form of “ancestor-descendant” relations;
  3. each record can have no more than one parent record and several subordinate records;
  4. graphically it can be represented as an inverted tree consisting of objects of different levels, where the vertices are the information units and the arcs are the links; 
  5. there is a single entry point; it is impossible to implement “many-to-many” relations;
  6. an example of such a model is the Windows Folder Catalogue.
  • Network:
  • represents data as a graph-like network structure;
  • any object can be connected with any quantity of the other elements;
  • there are several entry points;
  • graphically it can be represented as an oriented graph consisting of nodes (vertices) and links (edges) between nodes, each node can have multiple links to other nodes;
  • Relational:
  • it is oriented on the data organization in the form of two-dimensional tables (relations), where a table is a regular structure, it consists of similar rows  divided into the columns (attributes);
  • each row of a table must have a unique identifier called primary key;
  • normalization of the data is obligatory for the tables – minimization of the number of repeated data;
  • the distinctive feature of this model is the simplicity of data placement and ease of its interpretation;
  • it is the basis of most modern DBMSs.

As far as the other models are concerned, I will describe them in the upcoming posts, so stay tuned!