What should i prepare for back-end developer?

Question

I'm still beginner for this, and i need some advices or ways to become back-end dev. And also Where should i begin it?
Sorry for my bad english

Answer 1

For back-end developer you can learn Java to get data from database and display on the browser.

Answer 2

I'm not expert on the topic, but I think sql will be useful

Answer 3

Php also