sqlcourse.com http://www.sqlcourse.com/
sqlzoo.net https://sqlzoo.net/
Vertabelo Academy https://academy.vertabelo.com/
SoloLearn https://www.sololearn.com
SQLBolt https://sqlbolt.com/
codecademy https://www.codecademy.com/
MODE https://mode.com/sql-tutorial/
w3schools https://www.w3schools.com/sql/default.asp
Kaggle https://www.kaggle.com/learn
Udacity: SQL for Data Analysis