Introduction to SQL


Monday, 01 Oct 2018 Kudzai Nyandoro

SQL, pronounced "sequel", is an acronym that stands for Structured Query Language. According to Wikipedia, "SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from [...]" Dr. E. F. Codd who, in June 1970, published the journal paper "A Relational Model of Data for Large Shared Data Banks".

SQL is the standard language used in Relational Data Management Systems "RDMS"s. It is used to perform many tasks such as controlling, updating, creating, deleting, viewing, querying, modifying, data found in RDMSs. Examples of RDMSs are; SQL Server, Oracle Database, MySQL, SQLite, PostgreSQL and many more.

We are going to start with baby steps as usual by using the online programs that allow us to write and see how the tools works before deciding to install them onto our local machines. I have provided links to resources and online tutorial below to help the curious mind get started without having to install anything.

Learning SQL will lay the foundation for the upcoming web development tutorials and screencasts that I will be producing later on. When we get to developing web applications with Ruby on Rails or NodeJs, I will assume you already have knowledge of SQL, HTML, CSS, JavaScript, and Text Editors.

In my opinion, it really doesn't matter much which RDMS you choose at the beginning, I have tried Oracle, SQL Server, MySQL, and PostgreSQL and I use SQLite in my demo Rails applications. It's important to try as many of them as you can --slowly.

There is a slight difference in the SQL syntax among the RDMSs and when these differences pop up while coding your SQL, you can always use Google to search and find out and learn where these difference lie.

For example, I successfully completed an entire 21 hour long MySQL course where the instructor used MySQL and I used PostgreSQL to take the course. I learned a lot about both systems and the slight differences between MySQL and PostgreSQL. If I had to choose one of these, I would choose PostgreSQL.

So without further due, let us get started by visiting the online tutorials below. After getting a good idea of how SQL works we are going to start using PostgreSQL to learn more about SQL and also adding it to Ruby on Rails in later tutorials. The Codecademy course below is a very good SQL course to try out also.

Source
Wikipedia | SQLBolt | Techonthenet | CodeCademy