What is easier to read in EXISTS subqueries? [closed]

Question

It's a question of readability. There is no difference in performance.
_{Old versions of SQL Server were silly enough to look up meta data, but not any more.}

SELECT foo FROM bar WHERE EXISTS (SELECT * FROM baz WHERE baz.id = bar.id);
SELECT foo FROM bar WHERE EXISTS (SELECT 1 FROM baz WHERE baz.id = bar.id);

I am not considering NULL or "fun variants" which don't seem intuitive to me.

SELECT foo FROM bar WHERE EXISTS (SELECT NULL FROM baz WHERE baz.id = bar.id); SELECT foo FROM bar WHERE EXISTS (SELECT 1/0 FROM baz WHERE baz.id = bar.id);

The question popped up in comments just now. I researched the manuals of the most popular RDBMS:

• MS SQL seems to favor SELECT * in the manual.
• The example in the PostgreSQL 9.4 manual uses SELECT 1.
• Oracle 11g has SELECT * in the language reference.
• MySQL 5.7 has SELECT * in the reference manual but alsoSELECT 1 in the comments.
• SQLite has no example in the language reference.

A search on SO for code:"EXISTS (SELECT 1" yields 5,048 results.
A search on SO for code:"EXISTS (SELECT *" yields 5,154 results.
_{Updated links and counts 07.2015.}

So SELECT * has the popular vote and the big commercial RDBMS on its side.
I find SELECT 1 more intuitive. It's like saying "if at least one exists".
Is SELECT * more intuitive?

Answer 1

Intuitive is ...EXISTS (SELECT * .. because you really don't care

• The only keyword of importance is EXISTS
• The choice of ...EXISTS (SELECT 1 .. perpetuates the general myths and superstitions around EXISTS (eg comments on the MySQL docs).
• ANSI standard says "doesn't matter"
• It's more interesting to understand that EXISTS is a semi-join.