Dmitry Igrishin <dmitigr@gmail.com> 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 > as a prefix for the named parameters?
How are you going to distinguish named parameters from dollar-quote tags?
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.)
