These days, it’s not just data engineers who need to know SQL. As relational databases continue to proliferate across various fields, such as marketing and sales, a new cohort of professionals wants to learn SQL.

But there’s no need to shell out a bunch of money to learn these new skills. There are already plenty of free online resources that can teach beginners everything they need to know about SQL.

Here are the six best free resources for learning SQL.

Khan Academy

“Intro to SQL: Querying and managing data” by Khan Academy pairs video tutorials with interactive coding challenges for a best-of-both worlds course. Video lessons are shot at the command-line level, clearly demonstrating concepts in the code itself. Frequent coding challenges reinforce the educational content with diverse problem sets. This course is recommended for those who want to combine excellent visual lessons with interactive coding exercises.

SQLZoo

SQLZoo is an interactive, Wiki-based tutorial that offers lessons and projects for beginners in SQL. Students start with basic functions such as COUNT, SUM, and AVG, and end by building intermediate projects. The lessons center around interactive coding challenges that are meant to be self-explanatory. This is a good resource for students who want to learn SQL through small, simple exercises.

Codecademy

Codecademy, a leading educational coding platform, offers a free course on SQL. The course is structured as a series of interactive coding tutorials that guide students from basic functionality to varied, long-form projects. Codecademy’s deep reservoir of exercises, and the service’s sleek interface, make for a smooth learning experience. Recommended for students who want more of a professional feel to the learning process.

SQLBolt

SQLBolt combines easy-to-follow instructions, a simple interface, and interactive exercises to teach basic proficiency in SQL. Whereas many tutorials are purely coding-based, SQLBolt pairs written explanations with coding trials to give students a clearer and more robust overview of SQL. SQLBolt offers a middle ground between code-only tutorials and overly technical courses. The resource is recommended for students who thrive with text-based explanations backed up by standard exercises.

Udacity

The “Intro to Relational Databases” course by Udacity is a video course that’s jam packed with extensive SQL tutorials. Through a series of video lessons, the course teaches beginner and intermediate topics that will prepare students for many applications of SQL. While there are coding exercises, students must execute them in their own runtime environments, because the course does not offer interactive coding tests. This course is great for students who excel at learning visually.

SQL for Web Nerds

Developed by MIT Professor Philip Greenspun, SQL for Web Nerds is a somewhat advanced resource that demystifies the technical nitty-gritty of SQL in a clear and concise way. What the site lacks in flashy design, it makes up for in expert content. Greenspun’s resource offers thorough but concise explanations of SQL elements, but does not have interactive coding exercises. Students can use this resource with the previously discussed interactive coding courses to take their skills to the next level.

What are You Waiting For? Jump Right In, For Free!

With the recent explosion of data, different personnel and departments that were once far removed from relational databases are now interacting with them frequently. Marketers, salespeople, and many other non-tech professionals must learn some amount of SQL to take operations to the next level. And with so many free resources out there, no one should make a big monetary investment to do so.

The resources in this blog represent just a sliver of the free SQL resources on the web. Use these totally free resources, along with those that you find on your own, to learn the amount of SQL you need to take your career to the next level.