What is the best style to write sql? Is it camel case, or other?

Question

The best way to write sql

Answer 1

So SQL is case insensitive, but it is common to write keywords in Caps. Example:, SELECT a,b FROM c WHERE.....

Answer 2

Uppercase for the keywords. Snake case or camel case for the rest.

Answer 3

Uppercase is usual

Answer 4

Are the two ways right: " SELECT firstName FROM persons" and "SELECT first_name FROM persons" ?