Where can I code and practice SQL?

Answer 1

if you want only for pratice there is a app called sql code play try that link below:
https://play.google.com/store/apps/details?id=sql.code.play

Answer 2

To run sql online : http://www.sqlfiddle.com/

Answer 3

I think you can register for a free database in oracle site. I have done it previously