2017-08-27 18:13 GMT+03:00 Tom Lane <tgl@xxxxxxxxxxxxx>:
Dmitry Igrishin <dmitigr@xxxxxxxxx> writes:
> I'm working on finishing beta release of my C++ API for PostgreSQL. The
> library
> have simple SQL parser (preprocessor) to support the queries like that:
> SELECT :"column", $tag$constant string$tag$
> FROM :tables
> WHERE name LIKE :'name' AND
> sex = $1 AND
> age > $age
> where:
> :"column" is a variable which will be quoted as identifier (like in
> psql),
> :tables is a variable which will be not be quoted at all (like in psql),
> :'name' is a variable which will be quoted as literal (like in psql),
> $1 is a positional parameter,
> $age is a named parameter
> Is there are any contraindications/caveats/gotchas on using the dollar sign How are you going to distinguish named parameters from dollar-quote tags?
> as a prefix for the named parameters?
Well, since "The tag, if any, of a dollar-quoted string follows the same rules as an unquoted identifier ... ",
dollar-quote tags cannot contain spaces, right? This fact can be used to distingush
named parameters from dollar-quote tags.
If so, the only problem I see here is legalisation of spaces in the tags in future releases, for example:
select $foo bar$stuff$foo bar$;
I think you're going to end up with weird corner case behaviors if
you try to squeeze still another meaning into "$letters..."
But yes, probably it is better to use another syntax for named parameters. How about ":_parameter_"?
(Looks not so nice as "$parameter", but compatible with psql and can be used as easy query testing.)
Thanks!
