doc/src/sgml/query.sgml includes a tutorial example with this definition:
CREATE TABLE weather (
...
date date
);
The fact that "date" is used for both the column name and the type is
highlighted by two later comments:
(Yes, the column of type date is also named date. This might be
convenient or confusing--you choose.)
type names are not key words in the syntax, except where required to
support special cases in the SQL standard.
But as a documentation comment submitted recently points out, "date"
*is* a reserved word in the SQL spec:
http://www.postgresql.org/docs/current/interactive/sql-keywords-appendix.html
, just not in PostgreSQL. That makes using it as a column name in an
example an odd choice for a tutorial. The example is using the
ambiguity to point out where the line between what is and isn't legal is
at, and maybe that's a feature instead of a bug.
There are a few approaches that could improve on this:
-Keep all of that, but expand the description to link to "SQL Key
Words"--right now "SQL standard" doesn't go to that section--and say
this might be a reserved word in other SQL implementations. This is the
smallest useful improvement.
-Change the name of the column and remove the two related descriptions.
This will lose the lesson about where the parser's line is at.
-Do both: move this example of parser trivia somewhere else, but remove
it from the tutorial material by using a non-reserved column name there.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
