PostgreSQL is the first one I will mention, as it will be the database used throughout this guide. PostgreSQL is an open-source database system that is fully featured (which essentially means that you won’t miss any features compared to full-priced systems). Being open-source means that you don’t have to worry about licensing costs when developing and also provides other benefits such as tighter security and more stable releases.
You can’t talk about SQL database systems without thinking of Oracle. Oracle provides a robust and powerful solution that is utilized by many of the largest organizations in the world. However, it is proprietary and so utilizing it will mean purchasing licenses.
MySQL is another open-source SQL database solution. It is extremely popular in web development as it provides some built-in features that save time; however, it is limited in its abilities and feature set. MySQL owned and maintained by Oracle.
Microsoft has a solution for SQL Databases called Microsoft SQL Server (MSSQL Server). MSSQL Server is a fully featured solution that is used by many due to the integration with other Microsoft products and services. It is a proprietary product which means that you will need to pay for licenses.
As previously mentioned, all of these products listed use SQL and so by learning one, you have a foundation for the others. In these tutorials, the examples will be shown in PostgreSQL due to the full feature set, price, and availability.
It is recommended that this software be ran from a Linux machine. You can set up the latest Ubuntu Server LTS version on a virtual machine or even on a Raspberry Pi and run all of the aforementioned systems.