Re: polymorphic SQL functions has a problem with domains

On 2014-04-02 12:27:30 -0400, Tom Lane wrote:
> David Johnston <polobo@yahoo.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 &
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