SQL Fundamentals

SQL Fundamentals is a hobby-built project that’s trying to help you by summarizing most of the SQL information across the internet into just a couple of pages.

After reading this, you should have a fair amount of understanding of basic SQL, what it is, what is it used for, and how it works.

Now, you should be able to start practicing. There are lots and lots of tools (hackerrank, codewars, codeacademy, w3school, etc) that provide you with guidance and the needed tools to sharpen your SQL skills.