NULL value comparison - Mailing list pgsql-general

From Michael Sacket
Subject NULL value comparison
Date
Msg-id 9042C0C5-1A9E-420E-B143-7896FB9440A1@gammastream.com
Whole thread Raw
Responses Re: NULL value comparison  (Pavel Stehule <pavel.stehule@gmail.com>)
Re: NULL value comparison  (Adrian Klaver <adrian.klaver@gmail.com>)
Re: NULL value comparison  (David Johnston <polobo@yahoo.com>)
List pgsql-general
Good Day,

I'm trying to figure out why a postgresql query doesn't return what I'd expect with a query like this where there are
NULLvalues: 

select * from users where is_enabled<>'Y';

I'm expecting it to return all records where is_enabled is 'N' or NULL.  Perhaps my expectations are misguided.  Any
thoughtswould be appreciated. 

Thanks!
Michael


Example:

CREATE TABLE users (
    "name" char(50) NOT NULL,
    "is_enabled" char
)

insert into users (name, is_enabled) values ('Michael', 'Y');
insert into users (name, is_enabled) values ('Jeremy', 'N');
insert into users (name, is_enabled) values ('Sherry', NULL);


select * from users where is_enabled<>'Y';
+----------------------------------------------------+------------+
| name                                               | is_enabled |
+----------------------------------------------------+------------+
| Jeremy                                             | N          |
+----------------------------------------------------+------------+
1 rows in set (0.03 sec)





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