LEARNING COMPUTER AND DATA SCIENCE

Below you can find a few links to master various CS, SQL and data science skills from scratch and for free or at very low prices.

https://www.dataquest.io/
https://onemonth.com/
http://datamonkey.pro/
https://www.codecademy.com/
https://www.udacity.com/

DEVELOPING CODING SKILLS FOR FREE

Here are a few amazing resources to develop coding skills in various programming languages:

https://lagunita.stanford.edu/courses/DB/2014/SelfPaced/about
https://www.sqlteaching.com/
http://www.freecodecamp.com/
http://www.learncpp.com/