Re: Undefined psql variables

2017-01-23 18:53 GMT+01:00 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:

> Corey Huinker <corey(dot)huinker(at)gmail(dot)com> writes:
> > I was giving some thought to how psql handles undefined variables.
> > I would like an option where either psql can provide an alternate value
> > when an undefined variable is referenced, or a way to detect that a
> > specific variable is undefined and replace it with a defined variable.
>
> This seems pretty bizarre. What's the use case? Why would it not
> be better to build the behavior out of other spare parts, along the
> lines of COALESCE or perhaps
>
> \if not defined(x)
> \set x y
> \fi
>
> Obviously the \if stuff is things we don't have yet either, but
> it seems less likely to have surprising side-effects.
>

Some form of DEFINED has more sense than COALESCE in this case. We can
introduce some predefined client side functions available only in \if
\elsif statements.

Regards

Pavel

>
> regards, tom lane
>
>
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