Structured Query Language (SQL) is a programming language designed to work with relational databases, like SQLite, MySQL, and PostgreSQL. Due to SQL's effectiveness with large amounts of data, you can find it utilized heavily in many attractive software engineering, data science, data engineering, and data analytics positions.

This article is part of several articles about the best data-focused courses. For more, check out:

• Best Data Science Courses
• Best Machine Learning Courses
• Best Python Courses

SQL lets developers and data professionals store information in a format similar to spreadsheets in an Excel workbook.

In a SQL database, information is stored in tables made up of rows and columns; each row is a record, and each column defines an attribute in that record. Since developers have spent time organizing their business' data into nicely formatted tables, it becomes extremely space-efficient and searchable. This efficiency is why a lot of "big data" is still stored in SQL databases and why having a SQL skillset can help boost you into higher-paying careers.

The most recent Kaggle Machine Learning and Data Science Survey (taken in December 2020) asked respondents which programming languages they use regularly. The image below shows the professions and salaries for all of the respondents that said they commonly use SQL:

An RDBMS, such as PostgreSQL and MySQL, is the server software that holds your data and makes it queryable. Different systems have various advantages, disadvantages, and syntax, but most of those differences don't manifest until later in your learning. The core SQL language syntax applies to all relational database systems.

To get an idea of RDBMS popularity, we've pulled the following graph from the Stack Overflow 2021 Developer Survey:

If you're looking for my personal opinion, I would pick SQLite to start with for its ease of use, then move to PostgreSQL to learn how SQL servers work in the cloud.

To this day, most small projects of mine, such as web scraping, start out with SQLite and graduate to a Postgres cloud solution when needed.

For example, Postgres on Google Cloud Platform (GCP) was my choice for housing the data of Cardinal, a dictionary and language-learning app that has several million words and phrases for different languages.

Postgres isn't the best choice for all businesses and use cases. For example, Uber switched from Postgres to MySQL for various performance reasons specific to their use case. Another company might not face similar issues, and so the features Postgres offers over MySQL are more critical.

With that said, the course recommendation in this list start with SQLite and PostgreSQL, but we've also included MySQL and Oracle for completeness.

With a combination of professional SQL experience and many hours of research, we found the following SQL courses to be the top currently available.

For each course, we'll provide the basis for why it was chosen and what kind of learner it would suit best. But first, feel free to read about the criteria we used to determine good course candidates.

To cull down the massive number of data-centric courses to only those that are the most suitable SQL courses, we used the following metrics and heuristics:

• Relational Database Management System (RDBMS) used
• Ratings and social sentiment
• Syllabus breadth and depth
• Certification availability
• Quality of help from staff
• Inclusion of projects and quizzes

It's worth noting that all of the courses in this article offer a certificate, but unfortunately, many employers don't place much stock in certificates earned online. Employers do care about demonstrable experience through projects, which we'll touch on more in the learning section of this article.

Without further ado, let's jump into each course and talk about what stood out.

Best for: Those who have some programming experience, want one place for a comprehensive SQL course series using Postgres, and are interested in storing/querying text data.

Overview: As a whole, the comprehensiveness and execution of this course series make it number one on this list for learning SQL and Postgres. There are plenty of quizzes and projects to help you learn, as well as a highly active forum of students and TAs to help with any questions you may have.

Syllabus:

Coursera estimates that this course takes approximately four hours over four months to complete, or roughly 64 hours total.

Course 1. Database Design and Basic SQL in PostgreSQL

• Overall intro to Databases, SQL, and Postgres
• Modeling data
• Creating, inserting, querying tables
• Table relationships, such as one-to-many and many-to-many

Course 2. Intermediate PostgreSQL

• More, useful SQL syntax
• Aggregations
• Working with text
• Regular expressions

Course 3. JSON and Natural Language Processing in PostgreSQL

• More of a full treatment for text in Postgres
• Indexing and making text querying fast
• Using Python with Postgres
• Storing and querying JSON in Postgres

Course 4. Database Architecture, Scale, and NoSQL with Elasticsearch

• Intro to the problem of scaling databases
• How to use Elasticsearch with Postgres for querying text

As you can probably tell from the syllabus, text data is a big focus in these courses. While this Specialization is well-organized, informative, and very helpful for learning SQL, the last course gets some lackluster reviews. After going through that course's material, it looks like a good intro to Elasticsearch, a widely used technology, but the content could be completed in as little as a week.

Pricing and Certification:

As a member of Coursera Plus ($39/month), you can enroll in this Specialization and receive a certificate from The University of Michigan, which ranks 36th in the QS Engineering & Technology Rankings.

Enroll in PostgreSQL for Everybody

Best for: Complete beginners who prefer text-based, interactive learning, and are interested in data science. Also good for those enrolled in a video-based course but are looking for more projects to complete.

Overview: Dataquest's SQL Fundamentals course targets absolute beginners by teaching SQL through SQLite, a file-based RDBMS. After you complete the SQL Fundamentals course, Dataquest's platform lets you seamlessly transition to tracks, like Data Engineering, where you'll learn PostgreSQL and more advanced SQL concepts, as well as other data skills.

The Dataquest platform contains a variety of data-centric skill paths. For more about the platform, check out our DataCamp vs Dataquest review, but in short, Dataquest is a project-based, in-browser, interactive learning environment.

Syllabus:

• Database and table creation
• Filtering and Sorting data
• Aggregate functions and summary statistics
• Combining tables with Joins
• Subqueries and Common Table Expressions (CTEs)

And if you're interested, here's the SQL content from the Data Engineering track:

• Everything in the SQL Fundamentals
• Intro to PostgreSQL
• Prepared statements and SQL injections
• Loading and extracting data with tables
• Debugging Postgres queries
• Simple to advanced indexing

Pricing and Certification:

A Dataquest premium membership costs \$49/month or \$33/month paid upfront for a yearly plan. The premium membership gives you full access to everything on the website.

It's worth noting that approximately 1/3 of the content on the website is available for free, but you won't be able to earn certificates or access the projects section of the website.

Dataquest offers a certificate for every course or path completed, but certificates issued might not be considered credible by employers. Most of the value you'll receive is from the guided projects you'll create when on the learning path.

Enroll in SQL Fundamentals

Best for: Complete beginners with more of an interest in web development or working with MySQL over other RDBMS.

Overview: CodeWithMosh is dedicated to helping software developers improve their skills across various domains. Mosh's SQL course stands out for its coherent explanations and breadth of content. With 170 lessons over 11 hours of video, this was the most full-featured MySQL course we found.

Even if you don't plan on using MySQL, still check out one hour's worth of preview lessons and see if Mosh's teaching style gels with you.

Syllabus:

• Complex SQL queries
• Joins
• Views
• Stored procedures
• Functions
• Events and triggers
• Transactions and Concurrency
• Indexing
• Designing relational and secure databases

Pricing and Certification:

This course is available for \$19, but if you're interested in Mosh's other content, a subscription to the platform can be had for \$30/month.

All of the courses on CodeWithMosh come with a certificate upon completion, although employers that don't recognize the platform may not give the certifications a lot of value.

Enroll in Complete SQL Mastery

Best for: Total beginners with a strong interest in web development.

Overview: The amount of context put into each SQL lesson stood out the most with this course. Several chapters include a very realistic data project, such as storing information for an Instagram clone. The instructor provides an end goal and then builds queries step-by-step, explaining his logic along the way.

This course is ideal for those interested in web development with Node.js since a large portion of the course walks you through building an example web app using Node and MySQL. If you're interested in Python or using SQL for data science, you're better off with one of the other courses in this list.

Syllabus:

This course has got approximately 20 hours of content.

• Creating databases and tables
• CRUD (create, read, update and delete)
• String and aggregate functions
• Refining selections
• Introduction to web app development with Node

Pricing and Certification:

This course is available for \$80. However, Udemy courses frequently go on sale (at the time of writing, the course was on sale for just \$20).

As with all Udemy courses, the course provides a certificate of completion. However, Udemy isn't accredited, limiting the value of Udemy certificates to employers.

Enroll in The Ultimate MySQL Bootcamp

Best for: Those wishing to learn Oracle's SQL RDBMS in the context of passing interviews and certifications.

Overview: Oracle has excellent scalability and performance, making it a good choice for data warehousing and online transactional processing. As a result, it's a helpful tool for database administrators (DBAs), data engineers, and software engineers.

If you'd prefer learning SQL through Oracle, the instructor for this course provides a great intro into structuring queries properly and the tools required to work with Oracle effectively.

Syllabus:

This course has got approximately 16 hours of content.

• Database basics
• Single table queries
• Single row functions
• Grouping functions
• Multi-table queries and joins
• Analytical functions
• Creating, altering, and updating objects

You may have heard of Amazon Web Services (AWS) or Google Cloud Platform (GCP), but Oracle also has a cloud platform called Oracle Cloud Infrastructure (OCI). Unfortunately, OCI isn't yet as well established as AWS or GCP. Although this course doesn't cover how to use OCI, it does provide a strong starting point if you want to learn more about OCI in the future.

Pricing and Certification:

This course is available for \$80 (on sale for just \$20 at writing).

Like the other Udemy courses, this course provides a certificate of completion for working through its content.

Enroll in The Complete Oracle SQL Certification Course

Best for: Those at the intermediate level wishing to learn more about performance and optimization.

Overview: Once you've learned the basics and built a small project with SQL, it would be prudent to start learning about your table design, query, and index optimization.

This course is one of the few self-contained resources that describes the performance issues you'll run into when working on larger, more complex databases.

Syllabus:

• How SQL executes queries
• Postgres tools for tuning
• B-Tree, Bitmap, and Hash indexes
• Nested loop, Hash, and Merge Joins
• Partitioning
• Materialized views
• Other optimization techniques

Pricing and Certification: This course is part of Linkedin Learning's platform, which you can subscribe to for $39.99/month. Like other platforms, subscribing to Linkedin Learning will grant you access to hundreds of courses, including all of the courses originally on Lynda, a course platform recently bought by Linkedin.

Upon completion, you'll receive a Linkedin Learning certificate, which you can display on your Linkedin profile.

Enroll in Advanced SQL for Query Tuning and Performance Optimization

Learning SQL is less straightforward than languages like Python simply because of the setup required to run SQL queries.

For example, unless you're fortunate enough to have access to a fully set up database already, you first need to install and run a Postgres server, initialize some tables, and insert data to start learning how to query a Postgres instance. Therefore, beginning with the right course is pivotal to having a smooth SQL learning experience.

Listed below are some common SQL interview questions we pulled from various sources. If you're interested in a SQL interview platform, check out StrataScratch, which lists hundreds of SQL questions tagged by company and level. Working through interview questions is an excellent way to practice when you're in between projects.

Example questions:

1. What are joins in SQL?
2. How would you determine if two table columns were correlated?
3. What is a primary key?
4. Write a query to find how many missing values are in a table column.
5. What does DML stand for?
6. Explain the difference between WHERE and HAVING
7. What does UNION do?
8. What is meant by "normalization"?
9. Explain the difference between a database and a data warehouse.
10. What does ACID stand for?

It's worth noting that working through any beginner courses listed should equip you to answer these questions. Some courses will focus more on specific topics than others, so if you can identify which areas you think you'd struggle with the most, then comparing this with course syllabi may help you decide.

The questions above is just a small sample of what could appear in interviews. A great beginner SQL course will get you roughly 80% of the way to answering many entry-level questions.

Next, I'll describe a checklist of SQL topics you should expect to learn to be proficient in the language and interviews.

All relational database systems use the core SQL syntax. Due to the similarities, once you have the SQL basics of one system down, it's pretty easy to apply your knowledge any of the other RDBMS.

As a result, don't be put off by a course that appeals to you just because you might prefer to learn a different RDBMS first.

The following video from Socratica provides a good overview of the aspects to consider when picking an RDBMS to learn:

The value of a certificate is affected a lot by the reputation of its provider. Generally, if a certificate provider requires identity verification, it will carry more weight.

Racking up certificates doesn't necessarily prove to employers that you can do a particular job. Still, it is a good indicator that you're committed to self-improvement, which can be a very appealing trait if you can market it in the right way.

Ultimately, gaining a certificate won't guarantee you a job, but if you think of working through a course as just one part of your journey into the data industry, you'll be off to a great start.

In the absence of experience, the best thing you can do to prove your skills is to use your new knowledge to work on a few projects for your portfolio. Projects are a fantastic way to showcase and improve your skills and make for a great talking point in a job interview.

Learning is never one-size-fits-all. For myself, I struggle sitting through long videos and prefer coding exercises. However, it's important not to skip certain concepts in the long run, so figure out an approach that works for you.

My advice would be to periodically put new concepts on hold and find short projects you can do to consolidate your learning. These don't need to be huge, well-polished passion projects for your portfolio—those come later—all you need is an opportunity to flex your new data skills.

If you need inspiration, Kaggle has thousands of datasets you can work with for free, or even consider scraping your own data for an even more robust example project.

The data industry is becoming more and more accessible, so having zero experience shouldn't deter you. There's a lot to learn, so the best thing you can do is stop overthinking and jump right in.

Good Python and SQL skills will be incredibly helpful, so my advice would be to start learning one of these before worrying about all of the specific things you need to know. If you're more interested in Python, check out this article which showcases how the LearnDataSci team used data analysis to determine the best Python courses.

Out of the hundreds of SQL course options we reviewed, our #1 recommendation is PostgreSQL for Everybody for its execution, resources, community, and breadth of content.

Coursera certifications are also some of the most highly recognized, as far as online course platforms go. The Coursera membership isn't free, but if you're paying one-off prices for many courses, then the costs can add up quickly, making a recurring membership worthwhile. With that said, Udemy courses go on sale all the time, so if you're confident that a course will give you everything you need, some of them provide incredible value for the money.

LearnDataSci aims to deliver content for data science learners, so if you're interested in learning SQL purely in the context of data science, then starting with the Dataquest SQL course would be an excellent option for you.

When learning programming skills, the best advice is just to get started. While it's essential to pick a course that's right for you, all of the courses listed in this article are of high quality, containing more than enough information to forge new SQL skills. Where possible, we'd recommend trying out a course for free first and then committing to it if it feels like a good fit for you.

If you have any questions or feel like some great courses were missed, let us know in the comments below!