Introducing SQL

SQL was created in the 70s and by the end of the 80s, had become the de facto standard to interact with Relational Databases (RDBs), and it now powers most of the data management industry in the world.

Given its huge footprint and powerful abstractions, SQL has become a standard that anyone working with database systems eventually becomes familiar with. The expressive power of SQL is well understood and its knowledge is so ubiquitous that it has been taken into use beyond RDBs, with Database Management Systems (DBMSs) of all sorts providing a SQL interface even on top of many non-RDB systems.

Some of the great advantages of SQL are as follows:

• The core SQL functionality was standardized in the 80s and yet SQL is still very much alive and well, evolving and adding new powerful functionalities as data management evolves while maintaining compatibility with previous versions.

Every database has its SQL quirks, but the logic is the same and most SQL code will work on multiple databases with little or no change.

Learn it now and use it forever, and with (almost) every database.

• At its core, it has a simple, rigorous, and powerful syntax that reads like English sentences, so even non-tech people can grasp the basic idea, while professionals can express exactly what they want in a precise and concise way.

Most people can probably get a sense of what the following SQL does:

SELECT ORDER_ID, CUSTOMER_CODE, TOTAL_AMOUNT
FROM ORDERS
WHERE YEAR(ORDER_DATE) = 2021;

• With SQL, you work at the logical level, so you do not have to deal with implementation details, and it is a declarative language; you describe in a rigorous way what you want to achieve, not how to do it. The database engine has the freedom to store data, be implemented, and perform the request in its own way, as long as it produces the correct result according to SQL specifications.
• With a single SQL statement, you can process one piece of data or billions, leaving the burden of finding the most effective way to the database and giving you some freedom from scale.