From: Tom Lane <tgl@sss.pgh.pa.us>
To: Darryl Dixon <darryl.dixon@gmail.com>
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18451: NULL fails to coerce to string when performing string
 comparison
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References: <18451-dc130ad59b7bd7c9@postgresql.org>
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 <CAMfewD3sqAr4eD25NZJvSnAp406+r6cVer-3=5HoQ1Nm0Wt6FA@mail.gmail.com>
Comments: In-reply-to Darryl Dixon <darryl.dixon@gmail.com>
	message dated "Wed, 01 May 2024 09:38:56 +1200"
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Date: Tue, 30 Apr 2024 18:07:01 -0400
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Darryl Dixon <darryl.dixon@gmail.com> writes:
> The bug is that:
> 1) The concatenation is not producing NULL, but rather Text, and yet the
> comparison fails regardless, and
> 2) The explicit CAST of NULL -> Text fails to remedy this.

I wonder what you think NULL means.  You certainly don't appear to
understand its semantics at all.  Every SQL data type allows NULL
as a value, so "casting NULL to text" doesn't change the value,
only what type the parser deems it to have.

> Further examples below:

Every one of these looks as-expected to me.

			regards, tom lane