Re: String Comparison and NULL - Mailing list pgsql-general

From Andreas Kretschmer
Subject Re: String Comparison and NULL
Date
Msg-id 20080429124407.GA9643@tux
Whole thread Raw
In response to Re: String Comparison and NULL  ("Pavel Stehule" <pavel.stehule@gmail.com>)
Responses Re: String Comparison and NULL  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-general
Pavel Stehule <pavel.stehule@gmail.com> schrieb:

> > ... and I do something like "select id where animal <> 'Cat';"  then
> > shouldn't 1, 3, 4 and 5 be picked?  As it is I only get 1, 4 and 5.
> > NULL is not 'Cat'.  I realize that if I were testing for NULL itself I

NULL is nothing, you can't compare something with nothing. As Pavel
suggested,


As Pavel suggested:

> In this case use operator IS DISTINCT FROM
>
> select id where animal IS DISTINCT FROM 'Cat';


Andreas
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