Re: proposal - assign result of query to psql variable

From: Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Phil Sorber <phil(at)omniti(dot)com>, Erik Rijkers <er(at)xs4all(dot)nl>, David Fetter <david(at)fetter(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: proposal - assign result of query to psql variable
Date: 2013-02-02 11:25:45
Message-ID: CAEZqfEdUmCiHOfcwO82Y4iTKvPG0F1Jz_6xitj=N4q8_pNt7Mw@mail.gmail.com
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On Sat, Feb 2, 2013 at 7:30 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
> possible variants
>
> a) don't store NULL values - and remove existing variable when NULL
> be assigned - it is probably best, but should be confusing for users
> b) implement flag IS NULL - for variables
> c) use nullPrint
> d) use empty String

+1 for a). If users want to determine whether the result was NULL, or
want to use substitute string for NULL result, they can use coalesce
in SELECT clause. Anyway the feature should be documented clearly.

--
Shigeru HANADA

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