[![enter image description here](https://i.stack.imgur.com/qh2zK.png)](https://i.stack.imgur.com/qh2zK.png)
How do I create a field of data type `varchar` in my controller class with size as 20?
Also, could anyone please tell me how to create a field of data type `none`. Also, how to mention the fields to be mandatory?

I am quite beginner in this. Any help would be appreciated.