There's a lot of buzz in the tech world about data–but of course, raw data isn't very useful on its own.
SQL (usually pronounced like the word “sequel”) stands for Structured Query Language. Essentially, it's a language that allows communication with databases in order to manage all the data they contain. That's the shortest possible version; for the long version, keep reading this guide to SQL!
In the 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.
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.
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 (structured query language) is a programming language that enables programmers to work with that data.
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 SQL (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.
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
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 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 examples:
CREATE DATABASE name_of_a_database – creates a database;
CREATE TABLE name_of_a_table (
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 is responsible for creating a new table inside a particular database.
Which Industries Use SQL
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 the industries that mostly commonly use SQL.
In the finance industry, banking applications and payments processors such as Stripe store and operate data about financial transactions and users. Behind these processes is a complicated database. 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, 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, SQL is being used to drive these databases. From the social networks on your phone to the apps on your computer, these 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.
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 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.
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.
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.
A major competitor to MySQL, PostgreSQL is 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.
Chosing a 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.
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, will tell you the common mistakes that developers make when writing SQL, and how to avoid them.
Here are some popular books for learning SQL.
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- SQL Cookbook: Query Solutions and Techniques for Database Developers – 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 – teaches you SQL from the very basics
- Sams Teach Yourself SQL In 10 Minutes, by Ben Forta – covers SQL in an approachable, beginner-friendly way
- Getting Started with SQL: A Hands-On Approach for Beginners – a short and concise guide for beginners
- SQL QuickStart Guide: The Simplified Beginner's Guide To SQL – 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.
Online Courses For Learning SQL
Besides books, you can also get started with SQL by taking a free online course.
Here are some of the best courses for learning SQL.
- Codecademy’s SQL Course – for beginning developers
- Intro To SQL Course by Khan Academy – for beginning developers
- Stanford’s Online SQL Course – for intermediate developers
- Udacity’s Intro to Relational Databases Course – for intermediate developers
- Microsoft Virtual Academy’s SQL Coursework – for advanced developers
Where to Ask for Help
In your programming journey, there will be times where you get stuck on an SQL problem or other coding challenges. Books and SQL guides can only take you so far sometimes. Turning to online coding discussion sites is one of the best ways to get help. Programmer sites such as Stack Overflow provide you with free help from experienced programmers.
Here are some Q&A sites to check out:
- Stack Overflow – discussion site for programmers, covering SQL and many other topics
- Quora – Q&A site where you can ask more conceptual questions
- Reddit – Reddit has a sizable community of programmers who hang in subreddits like r/SQL.
- StackExchange – StackExchange has numerous discussion sites for various programming topics
Accelerate Your SQL Learning With Projects
The best way to accelerate your SQL learning is to work on projects. There's no need to start big here. Once you learn the basics, find a small project that involves making use of SQL, then write the code for that.
For example, you could create a database that organizes your music collection. You could also write a small web app that connects to a database system such as MySQL or PostgreSQL. As you improve your knowledge, you can tackle progressively larger projects.
Daily coding practice and coursework will improve your skills very quickly. When applying for a junior position, it should be enough to have at least one successful project done. This will prove that you have basic skills like creating a database, connecting it to the application, and operating (input, edit, output) data from the application.
To reach an advanced level, you should work on real projects and real cases that will help you to master your skills and gain a lot of unique experience.
Ready to Teach Yourself SQL?
Now is a great time to learn SQL. As the top programming language for databases, SQL is used by many companies in almost every industry. If you want to learn an in-demand skill, SQL is the way to go! Use this beginner's guide to SQL to find the resources you need and start your journey.
About the author
Anastasia Stefanuk is a passionate writer and a marketing manager at Mobilunity. The company provides professional staffing services, so she is always aware of technology news and wants to share her experience to help tech startups and companies to be up-to-date.