Link
Click here for link to the website.
About SQLBolt:
“Introduction to SQL
Welcome to SQLBolt, a series of interactive lessons and exercises designed to help you quickly learn SQL right in your browser.
What is SQL?
SQL, or Structured Query Language, is a language designed to allow both technical and non-technical users query, manipulate, and transform data from a relational database. And due to its simplicity, SQL databases provide safe and scalable storage for millions of websites and mobile applications.”