Re: Problems with question marks in operators (JDBC, ECPG, ...)

A Google search suggests Oracle 9.x supports a unary '?' operator (fuzzy
match), so the use of '?' in an operator name is not without precedent.

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*Mike Blackwell | Technical Analyst, Distribution Services/Rollout
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On Tue, May 19, 2015 at 10:03 AM, Bruno Harbulot <
bruno(at)distributedmatter(dot)net> wrote:

>
>
> On Tue, May 19, 2015 at 3:23 PM, Kevin Grittner <kgrittn(at)ymail(dot)com> wrote:
>
>> David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com> wrote:
>> > On Mon, May 18, 2015 at 3:31 PM, Bruno Harbulot <
>> bruno(at)distributedmatter(dot)net>wrote:
>>
>> >> In the discussion on the OpenJDK JDBC list two years ago
>> >> (
>> http://mail.openjdk.java.net/pipermail/jdbc-spec-discuss/2013-February/000050.html
>> ),
>> >> Lance Andersen said "There is nothing in the SQL standard that
>> >> would support the use of an '?' as anything but a parameter
>> >> marker.".
>>
>> > ​"​CREATE OPERATOR is a PostgreSQL extension. There are no
>> > provisions for user-defined operators in the SQL standard."
>>
>> Exactly. The standard specifies the characters to use for the
>> predicates that it defines, and provides no mechanism for adding
>> additional predicates; but who in the world would want to exclude
>> all extensions to the standard?
>>
>
> I was certainly not suggesting custom operators should be excluded. I was
> suggesting using something that was actually not incompatible with the SQL
> standards (and, even with standards aside, the expectations implementors
> have regarding the question mark, since it affects other tools too).
>
>
>
>> > ​And by extension if indeed the standard does require the use of
>> > "?" for parameters we are in violation there because the backend
>> > protocol deals with $# placeholders and not "?"​
>>
>> We're talking about a different specification that has question
>> marks as parameter placeholders. That's in the Java Database
>> Connector (JDBC) specification. (It is apparently also specified
>> in other documents, although I'm not familiar enough with those to
>> comment.) Note that it would create all sorts of pain if both the
>> SQL statements and a connector issuing them used the same
>> convention for substituting parameters; it is a *good* thing that
>> plpgsql and SQL function definitions use a different convention
>> than JDBC!
>>
>
> Actually, we were not just talking about JDBC. I don't know the
> specifications in details, but the SQL:201x (preliminary) documents linked
> from
> https://wiki.postgresql.org/wiki/Developer_FAQ#Where_can_I_get_a_copy_of_the_SQL_standards.3F
> seem to have some information. The Foundation document (Section 4.25
> Dynamic SQL concepts) says that dynamic parameters are represented by a
> question mark.
>
> In addition, the BNF grammar available at
> http://www.savage.net.au/SQL/sql-2003-2.bnf.html#dynamic%20parameter%20specification
> also says:
> <dynamic parameter specification> ::= <question mark>
>
> I'm not familiar enough with these documents to know whether I'm missing
> some context, but it would seem that the question mark is a reserved
> character, beyond the scope of JDBC (at the very least, it seems
> incompatible with Dynamic SQL and its implementation in ECPG).
>
> Best wishes,
>
> Bruno.
>
>