Introducing SQL and Relational Databases

SQL, An International Standard Database Language

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In this video, SQL expert Allen Taylor covers the basics of SQL. This video segment explains where SQL comes from and where it is today.

Keywords

  • SQL
  • IBM

About this video

Author(s)
Allen Taylor
First online
12 January 2019
DOI
https://doi.org/10.1007/978-1-4842-3841-7_1
Online ISBN
978-1-4842-3841-7
Publisher
Apress
Copyright information
© Allen Taylor 2019

Video Transcript

Speaker: In this course, I’ll introduce you to SQL and to the Relational Databases that SQL operates on. I’ll give you a little history so that you’ll see the context within which SQL was developed. People have been storing and using data for a long time, but it has only been relatively recently that they’ve been storing large quantities of data in an easily retrievable form. That easily retrievable form is the Relational Database. Relational databases are based on a theoretical construct called the relational model. To truly understand relational databases, you must understand the relational model first. There are several aspects to it, which we will discuss. We’ll also talk about some of the sources of confusion about the components of a relational database. Functional dependencies, keys and modification anomalies are important concepts that if misunderstood, can ruin the reliability of a database. To protect against the dangers of modification anomalies, you can normalize the databases’ relational model. Normalization can be tricky, but applying a few key concepts can protect you from problems.

In the information technology field, a lot of job descriptions list knowledge of SQL as a desirable or even a mandatory skill for anyone seeking the job being described. So what is SQL? It’s a computer language that was created decades ago by IBM that you can use to create, maintain and query relational databases. When IBM created the language, they named it SEQUEL. All caps, because it’s an acronym for Structured English Query Language. They gave it that name because one of the things you can do with it is craft queries that retrieve information from a database. The structured English part of the name refers to the fact that the syntax of the language is very similar to the syntax of ordinary English, but it’s more rigidly structured than ordinary English. When IBM got ready to release the language as a product, they discovered that another company had already copyrighted the name SEQUEL for an unrelated product. IBM solved the problem by dropping the vowels and calling their language SQL. Officially, the language is pronounced SQL. But the IBM people were accustomed to calling it Sequel and they continued to do so. As use of the language spread throughout the database industry, the Sequel pronunciations spread too. Today, about half the people call it SQL and the other half call it Sequel. SQL has become the industry’s standard language that’s maintained by an internationally recognized standards body. It’s the language of choice for virtually all relational database products in use today.