Posted by José Lopes.

This post initiates a series about databases. On a first part I will write about the database theory leaving for a later occasion other subjects like SQL.

The theoretical part will consist in what is a database and a database management system (DBMS), in focus on this post, what is a relational database, some terminology to be aware and finally the process description of a database design.

The goal with this set of posts is not to write in detail about subjects that you can easily find on the web, but is to structure some concepts that we then to neglect during our daily activities and that end to be decisive to our project success.

Let us start by what really is a database. Those who work with databases, on a level above user, are certainly aware that a database by itself is nothing magic and it does nothing alone.

A database is nothing more than a structured collection of records or data.

When we start to talk about computers and databases we arrive to the DBMS. The computer will use software to modulate the database structure, following some mathematical database model like for instance the relational, organizing in this way the data storage.

The DBMS is the software used to organize and keep the database, being labeled accordingly to the database model that it supports (its name is associated to the model it uses, for example when it uses a relational model it is called Relational Database Management System - RDBMS).

In a simple diagram we have:

The DBMS doesn't requires any programing, i.e., we don't have to define or program what it has to do, it already has all the necessary requirements to manage the database.

We should not mistake this programing with the query operations that can be done with a database, using a language like SQL, or even the necessary work to create the database structure.

The DBMS is part of any database product like: Oracle, MySQL, PostgreSQL, SQLite, etc.