userid or user_id?

Question

Database

What is the correct userid or user_id in the database?

Answer 1

In spherical SQL in a vacuum, it is customary to use the snake case. But in practice, you should stick to the style adopted for the project.
SQL Style Guide

Answer 2

No difference.

Answer 3

user_id - i.e. snake case
PS www.sqlstyle.guide/ru