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Re: wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE

From: Andreas Wenk <a(dot)wenk(at)netzmeister-st-pauli(dot)de>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-docs(at)postgresql(dot)org
Subject: Re: wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE
Date: 2009-08-17 10:10:29
Message-ID: 4A892C95.3000701@netzmeister-st-pauli.de (view raw or flat)
Thread:
Lists: pgsql-docs

Andreas Wenk schrieb:
> Tom Lane wrote:
>> Hmm, it would be important to keep this in sync with the core-SQL
>> description of CASE, no?  (Section 9.16.1)
> 
> yes. And there is written "general" form and "simple" form. I like that.
> 
>> I can't say that I think "simple CASE" and "searched CASE" are good
>> descriptions of the two forms, but just switching them doesn't make it
>> much better.  And doing so would likely create as much confusion as
>> it eliminates.  Can we come up with some other phrases?
> 
> IMO it should be the same like in 9.16.1 - a "general" form and a 
> "simple" form. Then changing both sections would be ok, because in 
> 9.16.1 the simple form is mentioned after the general form.
> 
> Would it be correct to change it in this direction - or is this 
> logically wrong (change expression to value):
> 
> 38.6.2.4. Simple CASE
> 
> CASE expression
>     WHEN value [, value [ ... ]] THEN
>       statements
>   [ WHEN value [, value [ ... ]] THEN
>       statements
>     ... ]
>   [ ELSE
>       statements ]
> END CASE;
> 
> Maybe it could also be value-expression ... but that I don't like that 
> much.
> 
> Then we could go further with this:
> 
> 38.6.2.5. General CASE
> 
> CASE
>     WHEN boolean-expression THEN
>       statements
>   [ WHEN boolean-expression THEN
>       statements
>     ... ]
>   [ ELSE
>       statements ]
> END CASE;
> 
> The general form of CASE provides conditional execution based on truth 
> of boolean expressions. ...
> 
> I think with these changes, 9.16.1 and this two sections are working 
> together
> 
> Cheers
> 
> Andy
> 
> P.S.: I can provide a patch with the changes if we discussed it and are 
> willing to make a change

Hi,

before building a patch it would be nice to hear, if my approach to change the docu here 
is a good one ...

Thanks

Andy

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Next:From: Alvaro HerreraDate: 2009-08-17 16:10:10
Subject: Re: wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE
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Subject: Re: Help me to understand (documentation)

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