On Sun, Aug 09, 2015 at 08:06:11PM -0400, Tom Lane wrote: > Noah Misch <noah@leadboat.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.
If we raise a syntax error, then there should be very informative message, because pattern
true = 2 > 1 is probably relative often
and it is hard to find syntax error on this trivial expression