[racket] DB and named query parameters

From: Sean McBeth (sean.mcbeth at gmail.com)
Date: Sun Feb 16 14:09:49 EST 2014

But what about stored procedures? I don't seen any examples of calling an
SP using DB at all.

On Sun, Feb 16, 2014 at 11:14 AM, Sean McBeth <sean.mcbeth at gmail.com> wrote:

> aaah, okay, thanks.
> On Sun, Feb 16, 2014 at 11:13 AM, Ryan Culpepper <ryanc at ccs.neu.edu>wrote:
>> On 02/15/2014 05:11 PM, Sean McBeth wrote:
>>> All of the examples in the documentation for the db package use either
>>> question-mark placeholders or numbered placeholders, i.e.
>>> "select * from some_table where some_column = ?"
>>> "select * from some_table where some_column = $1"
>>> The three databases that I use (SQL Server, MySQL, and Postgres) all
>>> support the question mark syntax, but you can only refer to a single
>>> parameter once in a query with the question mark.
>>> MySQL and Postgres support numbered parameters, but SQL Server does not.
>>> Or at least, not that I'm aware of. I've never seen anyone use it that
>>> way, and I can't find any examples online.
>>> Regardless, I rather much prefer named parameters, anyway, as it makes
>>> the queries easier to read.
>>> "select * from some_table where some_column = $param1"
>>> I know MySQL, Postgres, AND SQL Server all can support this style (well,
>>> replacing $ with @ for SQL Server), because I have a boat load of C#
>>> code doing it right now.
>>> But there is no indication of how to execute such a query in Racket with
>>> DB.
>> The PostgreSQL server itself only supports "$N" parameters. The MySQL
>> server (AFAIK) only supports "?" parameters.
>> Support for other parameter syntaxes may be added by the particular
>> library or driver you're using to communicate with the back end. For
>> example, I think ODBC drivers all support "?" placeholders.
>> The Racket db library doesn't add support for other parameter syntaxes,
>> and I have no plans to add it. (Not in terms of rewriting strings of SQL
>> code, anyway; possibly from a structured representation of SQL code.)
>> You could write the translation(s) using proper tokenizer(s) or regexps
>> that happen to work on the queries in your program and then create a
>> statement wrapper using prop:statement that would run the translator for
>> the appropriate dialect.
>> Ryan
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