| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | David Johnston <polobo(at)yahoo(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: polymorphic SQL functions has a problem with domains |
| Date: | 2014-04-02 16:32:30 |
| Message-ID: | 20140402163230.GP3750@awork2.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
On 2014-04-02 12:27:30 -0400, Tom Lane wrote:
> David Johnston <polobo(at)yahoo(dot)com> writes:
> > Does something like:
> > SELECT ($1 + $2)::$1%TYPE
> > exist where you can explicitly cast to the type of the input argument?
>
> I don't think SQL-language functions have such a notation, but it's
> possible in plpgsql, if memory serves.
Sometimes you can play nasty tricks using COALESCE() to force a cast
like that.
E.g. SELECT COALESCE(NULLIF($1, $1), $1 + $2);
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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