comment_post_ID

Where are you referring to?

In the database (top left corner), and in the source code. Every other field/column name that ends in _id uses lowercase other than those two.

What about wp_posts and wp_users? They use the capital ID.

But seriously… As far as I can guess it’s like that becuase “that’s how it’s always been” from the start, and changing that now would mean that any code that searches for or uses those columns would break horribly. In that sort of case it’s best to leave it be for the sake of backward compatibility, even if it doesn’t match most of the rest of the schema.

catacaustic nailed it in one ?? We try NOT to uproot the DB if we can help it.