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From: Bruce Momjian <bruce@momjian.us>
Message-Id: <201105100104.p4A14n024448@momjian.us>
Subject: Re: boolean states
In-Reply-To: <4DC0FFA5020000250003D243@gw.wicourts.gov>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Date: Mon, 9 May 2011 21:04:49 -0400 (EDT)
CC: jaime@2ndquadrant.com, jack@douglastechnology.co.uk,
	pgsql-docs@postgresql.org
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Kevin Grittner wrote:
> Jack Douglas  wrote:
>  
> > There are two kinds of people on this earth, those who understand
> > boolean arithmatic and those who don't. I'm not one of them.
>  
> Hmmm...  From that, I don't know if you do.  Which do I record in the
> understands_boolean column of the database record for you?  Dang, I
> knew I should have had *two* flags: known_to_understand_boolean and
> known_to_not_understand_boolean.  That would have been much simpler
> than allowing NULL for UNKNOWN....

Attached patch applied to HEAD and 9.0.X.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

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diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
new file mode 100644
index 657835c..c1a34fb
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
***************
*** 82,89 ****
       <member><literal>NOT</></member>
      </simplelist>
  
!     <acronym>SQL</acronym> uses a three-valued Boolean logic where the null value represents
!     <quote>unknown</quote>.  Observe the following truth tables:
  
      <informaltable>
       <tgroup cols="4">
--- 82,90 ----
       <member><literal>NOT</></member>
      </simplelist>
  
!     <acronym>SQL</acronym> uses a three-valued logic system with true,
!     false, and <literal>null</>, which represents <quote>unknown</quote>.
!     Observe the following truth tables:
  
      <informaltable>
       <tgroup cols="4">

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