@mirza-mam It looks like the database does not exist on you db-server. Make sure that it's created and if it is make sure you have the correct database name in you env
@Tray2
Actually, the problem was resolved. The reason I was continuously facing this problem was that, I was trying to create a Database from Ubuntu > mysql > CREATE DATABASE db_name command but in actual I have to create a database from my mysql db Users & Databases option.
In Digital Ocean the steps were like this:-
Login into your account.
Click your DB.
Goto Users & Databases.
Scroll down to "Databases".
Here add a new db name according to your requirements.
And the problem is solved :)