From: | David Gauthier <davegauthierpg(at)gmail(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Postgres General <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: How to get CASE statement to recognize null ? |
Date: | 2021-03-10 20:00:43 |
Message-ID: | CAMBRECCzpy0xek+=GdHu3H4N3jB4rT7D5gQZuDDssqYgeFsgrw@mail.gmail.com |
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Lists: | pgsql-general |
Hey, Thanks Tom !
It's actually a little more complicated than the simple example, so I'm not
sure it can be shoehorned into coalesce...
CASE
WHEN sr.nightly_cl_display_suffix is null THEN cast (d.p4_changelist
as varchar)
ELSE
cast (d.p4_changelist as varchar)||'-'||sr.nightly_cl_display_suffix
END as changelist
On Wed, Mar 10, 2021 at 2:46 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> David Gauthier <davegauthierpg(at)gmail(dot)com> writes:
> > dvdb=# select
> > CASE col1
> > WHEN null THEN 'z'
> > ELSE col1
> > END as col1,
> > col2
> > from foo;
>
> This test is equivalent to "col1 = null" which will always fail.
> You could try something like
>
> CASE WHEN col1 IS NULL THEN ... ELSE ... END
>
> Although I think the particular thing you're doing here would
> be better solved with COALESCE(col1, 'z').
>
> regards, tom lane
>
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