The 8 week SQL challenge is a set of eight different case studies designed to help people improve and master their SQL knowledge. I have taken this challenge to build on my already-solid knowledge of SQL to get a better understanding of how it would be used in different business scenarios. It has also given me the opportunity to think critically and come up with creative solutions to solve some extremely complex questions. You can find the website here.
This page shows the most difficult problems in one spot along with a more in-depth breakdown on my thought process on each one.