SQL Excerise

https://sqlbolt.com/lesson/select_queries_review



https://www.youtube.com/playlist?list=PL6EDEB03D20332309


https://www.wiseowl.co.uk/training/exercise-list/t-1141.htm

https://github.com/XD-DENG/SQL-exercise

https://sqlbolt.com/lesson/introduction

http://sqlfiddle.com/