ALL CAPS SQL

A while ago I read The Mac Is Not a Typewriter by Robin Williams. In it, the author claims:

Many studies have shown that all caps are much harder to read. We recognize words not only by their letter groups, but also by their shapes, sometimes called the "coastline." --pg. 31, The Mac Is Not a Typewriter

I've found this to be true. When we teach SQL, students are often surprised that we don't capitalize PostgreSQL keywords, preferring this:

select * from posts limit 5;

To this, which you might see in an SQL textbook:

SELECT * FROM posts LIMIT 5;

My arguments against the latter syntax: it's practically redundant in PostgreSQL, it's harder to type, and it's unnecessary because any good text editor highlights the keywords. Now I have another: such writing has been, in typesetting, shown to be harder to read. WHERE and LIMIT look similar from a distance in all-caps, but they mean and do different things.

It's a style opinion each developer gets to refine for themselves. To quote Williams: "Be able to justify the choice."