Now that you already have a database introduction let us talk about the database models. This is going to give you more insight on how it works ‘from the inside’.
Data base models determine how data can be stored, organized and manipulated in the data base. The most common database model is the relational model. Here are some of the different models:
It organizes data in a tree structure; therefore, there is a ‘parent’ and ‘child’ data segments. This means that a record can have repeating information, which can be found in the ‘child’ part.
A flexible way to represent objects and their relationships. It is a graph where object types are ‘nodes’ and relationship types are ‘arcs’. This model allows multiple parent and child records.
This database model is organized in tables with columns and rows. For instance, three key terms are used: relations, attributes and domains.
Named columns of a relation = attributes
Set of values that attributes are allowed to take = domain
The information of an entity (an employee from ‘X’ company) can be represented in rows and columns. The columns describe various attributes (employee’s name, address and phone number); the row is the instance of the entity (a specific employee).
Therefore, the employee (entity), and his data (attributes) are related.
Object Relational Model
It adds new storage capabilities to relational systems such as management of traditional (fielded) data and other complex objects like time-series, geospatial data and binary media (audio, video, images and applets).
It gives functionality to object programming languages, which means that applications require less coding, use data modeling, and it is easier to maintain code bases. Programming languages like C++, Smalltalk and Java are compatible.
Entity- Attribute- Value (EAV) data model
This model can be explained with Clinical Findings, where entity (first column) is the start and end of the patient’s examination; attribute (second column) is a description, data type, units of measurement, maximum and minimum permissible values among others. The Value depends on the data type (third column). Click on the image to enlarge.
Is there any other models with more common use?