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Thread: Reserved word "date" in tutorial example

Reserved word "date" in tutorial example

From
Greg Smith
Date:
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

Re: Reserved word "date" in tutorial example

From
Bruce Momjian
Date:
On Tue, May 21, 2013 at 10:19:45AM -0400, Greg Smith wrote:
> 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.

I reviewed this report and I can't see adding details to a tutorial
about the fact that other databases might use "date" as a reserved word.
I also can't see that renaming the field really add much.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + Everyone has their own god. +