Re: Documentation clairification?, CHECK constraints - Mailing list pgsql-general

From Bruce Momjian
Subject Re: Documentation clairification?, CHECK constraints
Date
Msg-id 200405192310.i4JNAvG06185@candle.pha.pa.us
Whole thread Raw
In response to Re: Documentation clairification?, CHECK constraints  ("Karl O. Pinc" <kop@meme.com>)
List pgsql-general
OK, patch applied.  Thanks.

---------------------------------------------------------------------------

Karl O. Pinc wrote:
>
> On 2004.03.31 10:53 Tom Lane wrote:
> > "Karl O. Pinc" <kop@meme.com> writes:
> > > But SQL has 3 valued logic (strictly speaking, not boolean).  It
> > > seems that the CHECK clases fail only when the expression result
> > > is FALSE, and pass when the result is either TRUE or UNKNOWN.
> >
> > Correct --- this is per spec.
> >
> > > Yes?  Should this be clarified in the documentation?
> >
> > Sure, send a documentation patch.
>
> --- create_table.sgml   Wed Mar 31 12:57:02 2004
> +++ create_table.sgml.new       Wed Mar 31 13:16:55 2004
> @@ -383,11 +383,14 @@
>        <para>
>         The <literal>CHECK</> clause specifies an expression producing a
>         Boolean result which new or updated rows must satisfy for an
> -      insert or update operation to succeed.  A check constraint
> -      specified as a column constraint should reference that column's
> -      value only, while an expression appearing in a table constraint
> -      may reference multiple columns.
> +      insert or update operation to succeed.  Expressions evaluating
> +      to TRUE or UNKNOWN succeed.  Should any row of an insert or
> +      update operation produce a FALSE result an error exception is
> +      raised and the insert or update does not alter the database.  A
> +      check constraint specified as a column constraint should
> +      reference that column's value only, while an expression
> +      appearing in a table constraint may reference multiple columns.
>        </para>
>         <para>
>
> Karl <kop@meme.com>
> Free Software:  "You don't pay back, you pay forward."
>                   -- Robert A. Heinlein
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
>

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