Re: expression evaluation with expected datatypes

2012/7/8 Tom Lane <tgl@sss.pgh.pa.us>:
> Pavel Stehule <pavel.stehule@gmail.com> writes:
>> When I worked on parametrised DO statement, I had to solve following issue:
>
>> Syntax is:
>
>> DO (param list) $$ ... $$ LANGUAGE ... USING expr_list
>
>> What is correct way for evaluation of expr_list with specified target types?
>
> I'd argue that that's a pointlessly unwieldy syntax that's creating an
> unnecessary problem.  Just use a SELECT list, that is
>
>         DO ... USING value AS name, value2 AS name2, ...
>
> The value expressions can define their own types just fine.

it is solution, but it is consistent with nothing what we support

* it is different than USING clause in other statements or in dynamic
SQL in plpgsql
* it is different than named parameter syntax

and I don't think so plpgsql style in main core is ok - when parser
returns some tree, but we use substring of queryString instead.

Regards

Pavel

>
>                         regards, tom lane