Re: Precedence of standard comparison operators

On Sun, Aug 09, 2015 at 08:06:11PM -0400, Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
> > In SQL:2008 and SQL:2011 at least, "=", "<" and "BETWEEN" are all in the same
> > boat. They have no precedence relationships to each other; SQL sidesteps the
> > question by requiring parentheses. They share a set of precedence
> > relationships to other constructs. SQL does not imply whether to put them in
> > one %nonassoc precedence group or in a few, but we can contemplate whether
> > users prefer an error or prefer the 9.4 behavior for affected queries.
>
> Part of my thinking was that the 9.4 behavior fails the principle of least
> astonishment, because I seriously doubt that people expect '=' to be
> either right-associative or lower priority than '<'. Here's one example:
>
> regression=# select false = true < false;
> ?column?
> ----------
> t
> (1 row)

> So yeah, I do think that getting a syntax error if you don't use
> parentheses is the preferable behavior here.

I agree.