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From	Navrátil, Ondřej
Subject	COALESCE documentation
Date	July 2 13:45:16
Msg-id	CAEELDaqnn5GayihUUhnKLR1_fegb-_b2i+4_dP4U192uK7j9vw@mail.gmail.com Whole thread Raw
Responses	Re: COALESCE documentation Re: COALESCE documentation
List	pgsql-docs

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Hello,

as per documentation

> The COALESCE function returns the first of its arguments that is not null. Null is returned only if all arguments are null.

This is not exactly true. In fact:

The COALESCE function returns the first of its arguments that is distinct from null. Null is returned only if all arguments are not distinct from null.

See my stack overflow question here.

Long story short

select coalesce((null, null), (10, 20)) as magic;

returns

 magic 
------- (,)
(1 row)

However, this is true:

select (null, null) is null;

Ing. Ondřej Navrátil, Ph.D.
IT Analytik
M +420 728 625 950
E onavratil@monetplus.cz

MONET+,a.s., Za Dvorem 505, 763 14 Zlín-Štípa
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Subject: Re: Missing information on '-X' in section 26.3.6.1.

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COALESCE documentation - Mailing list pgsql-docs

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