MIME-Version: 1.0
From: Igor Korot <ikorot01@gmail.com>
Date: Mon, 8 Dec 2025 18:39:46 -0800
Message-ID: <CA+FnnTw=18Rba2XgceRUFKQo5P7Xf9QhXT6wKF=DgzYT6K9-sw@mail.gmail.com>
Subject: How do I check for NULL
To: "pgsql-generallists.postgresql.org" <pgsql-general@lists.postgresql.org>
Content-Type: text/plain; charset="UTF-8"
Archived-At: <https://www.postgresql.org/message-id/CA%2BFnnTw%3D18Rba2XgceRUFKQo5P7Xf9QhXT6wKF%3DDgzYT6K9-sw%40mail.gmail.com>
Precedence: bulk

Hi, ALL,
Consider the following scenario:

CREATE TABLE test(a INT, b VARCHAR(256), c INT, d VARCHAR(256), /*
more fields follows*/);
CREATE UNIQUE INDEX test_x( b, c, d );

Now I try to do:

INSERT INTO test VALUES( 0, 'abc', 12345, (SELECT foo FROM bar),
/*more data follow*/);

My problem is:

The SELECT can either return data or NULL.
Everything is good when the data is returned, but the insert fails
when the NULL is returned, because the field "d" is a part of UNIQUE
INDEX.

However,, I'd like to still insert the record and I'd like to do something like:

INSERT INTO test VALUES( 0, 'abc', 12345, IF( (SELECT foo FROM bar) ==
NULL, "postgres", <select_result>), /*more data follow*/);

What would be the best way to achieve this?

Thank you..