What is SQL? A Beginner’s Guide to the SQL Language
Updated on June 28th, 2021 | Sign up for learn to code tips
There’s a lot of buzz in the tech world about data–but of course, raw data isn’t very useful on its own. That’s where a language called SQL (also called Sequel) comes in.
In this guest post, Anastasia Stefanuk explains what SQL is, the basics involved in SQL programming, which industries it’s most commonly used in, common SQL database systems, and how to start learning the language yourself.
Here’s Anastasia with her beginner’s guide to SQL.
Table of Contents
What Is SQL?
How to Use SQL
What Is SQL Used For?
SQL Database Systems You Should Know About
How to Learn SQL
Where to Ask for Help Learning SQL
How Long Does It Take to Learn SQL Language?
Disclosure: I’m a proud affiliate for some of the resources mentioned in this article. If you buy a product through my links on this page, I may get a small commission for referring you. Thanks!
These days, almost all businesses, from small online stores to Fortune 500 corporations, use data to run their operations. They manage this data using databases. Because of this, the demand for database administration experts has exploded, and because of this demand, working as a database developer, particularly an SQL developer, can be very lucrative.
In this article, we’ll look at what SQL is and why you might want to learn it.
Curious about learning SQL? Here’s a handy beginner’s guide.
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What Is SQL?
Data is a core part of many web applications and mobile apps. For example, an application like Facebook holds a user’s profile information, including data about their friends and posts. To hold this data, a database system is used. SQL is a programming language that enables programmers to work with that data.
What Does SQL Stand For?
SQL stands for Structured Query Language. Essentially, it’s a language that allows communication with databases in order to manage all the data they contain.
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How to Pronounce SQL
🗣️ SQL is usually pronounced like the word “sequel”. However, it’s a matter of preference (like gif vs. jif)—some people pronounce it in acronym form as all three letters, like “ess-que-el”.
Is SQL a Programming Language?
Yes, SQL is a programming language. It offers looping, logic directives, variables, and so on. However, it’s not a language in the same sense as, say, Java or C++.
SQL is considered a fourth-generation language (4GL), whereas Java and C++ are third-generation languages (3GLs).
Instead of being a programming language for building websites, apps, or software, SQL is a language that enables storing, retrieving, and manipulating data in databases.
History of SQL
SQL was first developed in the early 1970s by IBM researchers Raymond Boyce and Donald Chamberlin. It was initially called SEQUEL (Structured English Query Language) and was designed to manipulate and retrieve data in IBM’s database management system, System R.
In the late 70s, Relational Software, Inc. (now Oracle) was inspired to create their own version and introduced the first commercially available implementation of SQL.
By 1986, the American National Standards Institute (ANSI) and the International Organization for Standardization (ISO) had adopted a standard definition of SQL.
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How to Use SQL
While an application might be programmed in a language like Python, PHP or Ruby, databases are not configured to understand these. Historically, databases understand only Sequel (though this has changed significantly in recent years). Because of this, learning SQL is almost a must if you intend to work in web development or app development.
Like other programming languages, SQL has its own markup. This makes it necessary for a programmer to learn SQL markup before they can use it effectively.
Besides markup, another feature unique to database programming is the concept of tables. A database may be represented as a number of tables. Each table has its own number of columns and rows and represents a set of data.
📚 Imagine a library. We could create a database that stores data about books in the library.
In this case, we would need only one table:
This table would allow us to store all the information we need.
SQL Language Elements
SQL is made up of statements that start with a keyword or command, e.g. CREATE, and end with a semicolon.
Other SQL examples of language elements include:
Keywords: Words that are used to perform various operations in a database, such as ADD, JOIN, VIEW, etc. Here’s a list of SQL keywords.
Identifiers: The names of objects in the database, such as tables, views, indexes, columns, etc.
Expressions: A symbol or string of symbols that perform mathematical operations on data.
Search conditions: Used to select a subset of the rows from a table. Also allows you to create IF statements to specify whether a condition is true or false in a certain row or group of rows.
Data types: As the name suggests, the type of data that will be stored inside each column when creating a table. Examples include number, string, date and time, etc.
Nulls: Use a Null to specify that value that is unknown or missing.
Comments: Explains sections of SQL statements.
And much more.
List of SQL Commands
There are a few frequently used SQL commands you should be familiar with for database work. When working with databases, a programmer might write commands such as:
CREATE DATABASE – to create a database
CREATE TABLE – to create tables
SELECT – to find/extract some data from a database
UPDATE – make adjustments and edit data
DELETE – to delete some data
DROP – to remove tables and databases
INSERT INTO – to insert new data into a database
These are just the most common commands. The more complicated the database is, the more commands you as the programmer will need to use.
These Sequel commands are used when writing queries–inquiries that allow you to operate data in databases. In other words, when you enter these commands in a database system, the system interprets the commands and processes them. The result could be, for example, a new record in the database, or the creation of a new database.
Here are some quick SQL examples of queries:
CREATE DATABASE name_of_a_database – creates a database;
CREATE TABLE name_of_a_table (
column1 data_type,
column2 data_type,
columnX data_type );
The first query is responsible for creating a new database. For example, an app like Facebook might contain databases for each of the following:
Users – this database would store all the information about profiles of the users
Interests – this database would hold all the different interests that can be used to track the hobbies that users are into
Geographic locations – this database would hold all the cities around the world in which Facebook users live
The second query (CREATE_TABLE) is responsible for creating a new table inside a particular database.
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What Is SQL Used For?
Databases (and therefore SQL) are used in the technology field in almost every area where significant amounts of data are involved. Let’s look at some of the industries that most commonly use SQL.
💰 In the finance industry, banking applications and payment processors such as Stripe store and operate data about financial transactions and users. Behind these processes is a complicated database, which SQL is often used for. Moreover, bank database systems have extra security requirements that call for the highest levels of risk compliance in the SQL code used.
🎵 Music applications like Spotify and Pandora also make intensive-use databases. Among other things, Sequel databases help these apps to store vast libraries of music files and albums by various artists, operate this data to find what the user is looking for, store the data about users and their preferences, etc.
📱 Social media platforms involve a lot of data processing. Apps like Instagram and Snapchat use SQL to store a user’s profile information such as bio and location, to update the app’s database when a user creates a new post or shares a photo, and to record messages sent from one user to another so the user can retrieve the messages to read again at a later time.
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All around you, the SQL language is being used to drive these databases. From the social networks on your phone to the apps on your computer, so many pieces of software are running some version of SQL. With such universal applicability, you can see why this database programming language is such a useful tool to have in your developer’s tool belt.
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SQL Careers and Skills In Demand
SQL is one of the most in-demand skills among all jobs in data, appearing in 42.7% of all data job postings. In addition to dedicated SQL developer jobs, some careers that commonly require SQL skills include:
Database Administrator (DBA): Make sure that data is stored, organized, and managed properly to make it easier to retrieve data quickly and accurately.
Database Engineer: Plans, creates, and manages databases for a company.
Data Analyst: Sorts through massive amounts of data to draw important business insights from it. Data analysts use SQL to access, manipulate, and analyze data stored in a database.
Business Intelligence Analyst/Engineer: Analyzes data that is used to make important business decisions. Often supports statistical analysis initiatives.
QA Engineer/Tester: QA engineers and testers, like penetration testers, find, investigate, and report bugs in software. Needs to know SQL in order to verify that databases are functioning properly.
Software Engineer: Many software engineers either work directly or indirectly with databases, which means knowing SQL can be highly beneficial.
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SQL Database Systems You Should Know About
A database system is a program that allows a developer to work with databases with the help of a user interface. Database systems often have ready templates, builders, and constructors.
These tools make the life of a database programmer much easier. This is because such tools automate common tasks, such as cleaning up the database system.
Now let’s look at some of the most common SQL database systems. These systems are ranked based on DB-Engines popularity scores. The ranking takes into account the following variables:
Number of mentions of the system on websites, measured as the number of results in search engine queries
General interest in the system or frequency of searches in Google Trends
Frequency of technical discussions about the system
Number of job offers in which the system is mentioned
Number of profiles in professional networks in which the system is mentioned
Relevance in social networks
Oracle Database
Oracle is the leading SQL database system in the world. It’s used in a wide range of industries, but is particularly popular in data warehousing and online transaction processing.
➡️ Learn Oracle here: LinkedIn Learning’s Oracle Database 12c: Basic SQL
MySQL
This open-source database system is available for free to individuals and businesses. It’s highly popular with small businesses and startups since there’s no license fee. Because of its open-source model, MySQL is used in many open-source software programs and applications.
Curious about the difference between SQL and MySQL? The name can confuse some people, so when it comes to SQL vs. MySQL, remember that SQL is the language and MySQL is a database system. SQL and MySQL work together, but are completely different. You use SQL to access, update, and manipulate data stored in a MySQL database.
➡️ Learn MySQL here: LinkedIn Learning’s MySQL Essential Training
Microsoft SQL Server
SQL Server is Microsoft’s bespoke SQL database management system. This database runs on all major versions of Windows operating systems. It’s used in consumer software as well as on web servers that run Windows. It has a large user base.
➡️ Learn SQL Server here: Pluralsight’s SQL Server Fundamentals
PostgreSQL
A major competitor to MySQL, PostgreSQLis another free, open source database system. It’s used widely by technology startups for its free licensing model. PostgreSQL supports all major operating systems–MacOS, Windows and Linux. It places greater emphasis on following standard SQL syntax than other databases. Other databases (like SQL Server) greatly modify the SQL standard, making them harder to learn.
➡️ Learn PostgreSQL here: Pluralsight’s PostgreSQL: Getting Started
NoSQL
NoSQL (aka “not only SQL”) refers to a type of “non-relational” database (i.e., it does not use a schema of rows and columns found in most traditional database systems).
While SQL databases have a predefined schema, NoSQL databases allow you to store data in many different ways, depending on the requirements of the type of data being stored. NoSQL or non-relational databases include MongoDB, Apache Cassandra, and Couchbase. (You cannot use SQL to access these databases.)
➡️ Learn NoSQL here: Coursera’s Introduction to NoSQL Databases
Choosing a Sequel database system to learn can seem challenging given so many good choices. If in doubt, go with one of the free, open-source options such as MySQL or PostgreSQL.
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Where to Learn SQL
So how do you actually go about learning SQL as a beginner? Here’s a quick rundown of the steps:
Master the basics. Start by learning the basic SQL syntax. W3Schools has great SQL tutorials that can help you get familiar with the language.
Take a SQL course. Take a course to build up your SQL knowledge.
Work on real-world projects.Practice with real data + a database.
Below, find specific resources for where to learn SQL, including books and courses that will take you from beginner to advanced (and ready to hunt for SQL developer jobs).
The Best Books For Learning SQL
A well-written book on SQL will cover SQL and databases in-depth, giving you a firm grounding in the fundamentals. In addition, you will learn the common mistakes that developers make when writing SQL, and how to avoid them.
Here are some popular books for learning SQL.
Disclosure: The books below are available on Amazon. As an Amazon Associate I earn from qualifying purchases, so if you click one of the links below and buy a product, I may get a small commission at no extra cost to you.
SQL Cookbook: Query Solutions and Techniques for Database Developers (via Amazon) – covers the functionality of popular databases such as Oracle, SQL Server, and PostgreSQL
Head First SQL: Your Brain on SQL — A Learner’s Guide, by Lynn Beighley (via Amazon) – teaches you SQL from the very basics
Sams Teach Yourself SQL In 10 Minutes, by Ben Forta (via Amazon) – covers SQL in an approachable, beginner-friendly way
Getting Started with SQL: A Hands-On Approach for Beginners (via Amazon)- a short and concise guide for beginners
SQL QuickStart Guide: The Simplified Beginner’s Guide To SQL(via Amazon) – takes you from knowing absolutely nothing about SQL and databases to mastering core parts of database programming. The book builds up to advanced topics such as differences in SQL syntax among popular database programs.
Introduction to SQL by Launch School – Free ebook that walks you through how to manipulate and query data in modern relational databases.
Check out other programming books here. Online Courses For Learning SQL Besides books, you can also get started by taking an online SQL course.
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