Introduction to SQL

It doesn’t matter if you are a frontend, backend, or a full stack developer, knowing SQL is a must have skill.

What is SQL and why you should learn it

SQL stands for Structured Query Language.

It is pronounced SEQUEL.

SQL is a language designed to handle databases.

It allows you to manage and access data in a relational database using a standard approach.

Relational Database Management Systems or simply RDMS are the industry standard for storing data.

RDMS store data in tables, much like the ones you make in your Excel spreadsheets with columns and rows, each column is called a field and each row is a data entry called a record.

Some of the most common RDMS are PostgreSQL, MySQL, Oracle, and SQL Sever.

There are also NoSQL Databases like Mongo that store data in different ways such as documents, they are growing in use year after year, but are still far from becoming as widely used as relational ones.

SQL Usage

SQL is used in a variety of ways to manage your application’s data, such as to:

  • Retrieve, Update, Insert and Delete data
  • Create and Delete databases and tables
  • Manage permissions to certain data, so some users can access it and others don’t
  • Guarantee the integrity of the data
  • Automate actions in the database according to some change in the data

SQL Dialects

Be aware that there are some variations of SQL depending on the RDMS you are using that make SQL even more powerful for those specific systems.

After learning the standard SQL, it is common for some people to specialize in a particular RDMS and its specific dialect like Oracle’s PL/SQL or PostgreSQL’s PL/pgSQL.

It is also common to see people referring to standard SQL as ANSI SQL to differentiate it from the specific dialects.

ANSI stands for American National Standards Institute, the institute standardized SQL in 1986.