I've definitely recommended your service to my friends looking to learn SQL. Also, I made my share of contribution to the SQL pedagogy by writing blog articles

I've definitely recommended your service to my friends looking to learn SQL. Also, I made my share of contribution to the SQL pedagogy by writing blog articles on "SQL for Excel Users": http://blog.treasuredata.com/blog/2014/12/05/learn-sql-by-calculating-customer-lifetime-value-part-1/ http://blog.treasuredata.com/blog/2014/12/05/learn-sql-by-ca...