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What is SQL and what is it used for?

SQL is one of the most important programming languages to know if you work with data. We explore what it is, what it’s used for and which jobs you could land if you learn SQL.

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Data is everywhere, from the price of items at your local supermarket to the personal data collected from your browsing habits. Our world is built on data, and SQL is a programming language that makes navigating this data much easier. 

Besides exploring SQL and its uses, we’re going to look at how you can learn the language and the types of jobs you could get into if you pick up SQL. For instance, if you’re interested in working in the data industry, SQL is pretty essential learning.

What is SQL?

As we discussed in our article about what different programming languages are used for, Structured Query Language, or SQL for short, is a programming language that communicates with databases. The intention of SQL (often pronounced sequel) is to store, retrieve, manage and manipulate data within a database management system.

SQL was developed by IBM in the early 1970s and became commercially available in 1979. It is globally accepted as the standard relational database management system (RDBMS). 

It uses sets of keywords to retrieve data from databases, and these keywords are called statements. Later, we’ll take a look at some of the statements available in SQL.

What is a database? 

Databases are all around us, with almost every company and business needing to store information digitally. A database is a collection of organised data that can be easily stored, sorted, retrieved and searched. 

There are a variety of database types, and which type you use will be dependent on the type of data you wish to store. Let’s look at a few popular database types: 

  • Relational databases – these databases are laid out in rows and columns, store and provide data in multiple tables, and allow you to identify and access the data in relation to one another. All relational databases use SQL. Microsoft SQL Server is an example of a relational database management system.
  • NoSQL databases – this encompasses any database that does not use SQL as its primary language. These databases are better suited for those who do not want their data as structured. We’ll talk more about these databases later. CouchDB is an example of a NoSQL database.
  • Cloud databases – these are any database that runs within the cloud, access to these databases is provided as a service. They are low maintenance and offer flexibility. Oracle Autonomous Database is an example of a cloud database.
  • Time series databases – these are databases that have been optimised for time-stamped data, which offers more accurate insights. Druid is an example of a time series database.

What is SQL used for?

So, now you know what SQL is, you might be wondering what it is used for. As we mentioned earlier, it is a programming language used to communicate with relational databases. But let’s explore that a little further. 

SQL allows you to query the database in a variety of ways, using English-like statements. It’s used on websites for back-end data storage and data processing solutions (for example, Facebook uses SQL).

Other than Facebook, you can expect SQL to be used within music apps like Spotify, banking apps like Revolut and other social media platforms such as Twitter and Instagram. SQL is the most commonly used database language, so it can be used for almost any company that needs to store relational data.

Queries within SQL are used to retrieve data from the database, but the queries vary in efficiency. This is due to the fact that many databases have their own system-specific additional proprietary extensions.

Essentially, SQL provides CRUD functionality for databases. What does CRUD stand for?

  • Create
  • Read
  • Update 
  • Delete.

SQL statements 

If you were to navigate a large database without SQL, it would take a significantly longer time to find the data you need. 

By using the SELECT statement, you can select data by table and column types. This way, you can instantly pinpoint data sets that meet all requirements of your search rather than spending a lot of time searching manually. 

The INSERT statement allows you to add new information to the tables. Similarly to the SELECT statement, you can choose multiple columns to input your data into.

The DELETE statement does exactly what it sounds like: it allows you to delete existing records within a table. A DELETE query also allows you to specify rows that should be deleted that match specific conditions.

The CREATE DATABASE statement is the first step to setting up your database, it is used to create an entirely new database within your database management system. Likewise, CREATE TABLE is used to create a new table once the database has been created. 

The UPDATE statement is used to update one or more records within the database. You can either update all rows at once or use a condition to only alter a subset.

Types of SQL commands

The language can be broken down into four types of SQL commands – DDL, DML, DQL and DCL. Let’s look at each of these sections.

  • DDL (data definition language) – this is used to create and modify database objects like tables, users, and indices. 
  • DML (data manipulation language) – this is used to delete, add, and modify data within databases.
  • DCL (data control language) – this is used to control access to any data within a database.
  • DQL (data query language) – this is used to perform queries on the data and find information, and is composed of COMMAND statements only.

There are tools available to help you write SQL, some of these tools include Microsoft’s SQL Server Management Studio, DataGrip, Oracle’s SQL developer, SQL Workbench and Toad.


NoSQL databases came to prominence in the late 2000s in order to accommodate data with less need for an upfront structure. These types of databases tend to be easier for developers, as they sometimes have faster queries and more flexible data models.

In comparison, SQL-based databases are used specifically for relational data. They allow for flexible query use, are well structured and have a reduced data storage footprint. SQL databases are far more common than NoSQL, but frequently they are used together.

There are some major differences between the two, these include:

  • Scalability – NoSQL databases tend to be horizontally scalable, whereas SQL databases are more often vertically scalable. This means that NoSQL databases can often handle higher traffic numbers.
  • Structure – SQL databases have a table-based structure, but NoSQL databases can be graph-based, document-based or wide column stores. SQL databases are better suited for multi-row transactions.
  • Knowledge and community – There is a huge range of information and communities available for SQL since it is more common and has been around for longer. NoSQL does not share this number of forums and resources, so it may be harder to seek help when needed.

Types of SQL jobs

Learning SQL will open up opportunities in a range of different careers. Let’s take a look at some of the options available.

Data scientist

A data scientist is an analytical data expert – they extract, analyse and interpret big data from a range of sources in order to solve problems. SQL is crucial to data scientists as databases are at the core of their work due to the data analytics they have to carry out. 

Check out this in-depth data science course if you are interested in learning more about this career option.

SEO analyst

An SEO analyst analyses data and optimises site content in order to increase organic search traffic. SQL is beneficial to this role as they work with a lot of big data, and databases are far stronger than excel documents which are often used. 

If the idea of an SEO role interests you, why not try our SEO and WordPress training course to get started?

Software engineer

A software engineer develops and builds computer systems software and application software. Being a software engineer requires knowledge of programming languages in order to build the software, and most programmers are required to have some knowledge of SQL.

If you’re interested in becoming a software engineer, our ExpertTrack on software development fundamentals will guide you through some of the essentials.

Business analyst

A business analyst analyses data and documents market environments to advise business decisions. This role massively ties into SQL as it is very data heavy, and you’ll almost definitely be working with relational databases.

To learn more about data for business, check out this incredible course on business analytics

As well as SQL being useful to get you into one of these roles, it can also be beneficial to those with their own business or plans to start one up. Relational databases can help you store, sort and modify huge amounts of data.

How to learn SQL

Taking that first step to learn a programming language may seem daunting at first, but with patience and dedication, you can reach your full potential. Start off with the basics and gradually move on to more advanced commands when you’re ready. 

Thankfully, there are many online courses and resources available to help you learn this useful language. Trying out a course, such as our introduction to databases and SQL, is a great place to start. 

As well as online courses, another great way to learn is to watch video tutorials and become comfortable with the methods and software used.

One of the best ways to retain any information you learn and remember the SQL commands is to practise. You can download a free SQL database management system such as MySQL and put your knowledge to the test, playing with the functions and exploring the database.

There are even websites that simulate an SQL management system such as SQLfiddle. On sites like this, you can play around with writing statements without the need to install any software.

Once you are comfortable with your SQL knowledge, you can start working towards an SQL certification. This will look great on your CV, and will really boost your chances of getting one of those SQL jobs mentioned above. 

Final thoughts

Whether you want to upskill in your current role or find a new career altogether, SQL is a very powerful and useful language to learn. We hope this article has equipped you with the knowledge to get out there and start learning the language yourself.

If you’re ready to start your SQL journey now, why not check out our courses on SQL for data analytics, data query with Transact-SQL, and saving and structuring data?

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