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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: 2009-08-14 21:39:07
Message-ID: 4A85D97B.9040105@netzmeister-st-pauli.de (view raw or flat)
Thread:
Lists: pgsql-docs
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




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