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From "Dag H. Wanvik" <Dag.Wan...@Sun.COM>
Subject Re: [jira] Commented: (DERBY-165) Droppping columns with ALTER TABLE errors out
Date Wed, 06 Jul 2005 17:37:32 GMT

Hi Daniel,

>>>>> "DJD" == Daniel John Debrunner <djd@debrunners.com> wrote:

DJD> > Derby does not support dropping columns, cf
DJD> > http://incubator.apache.org/derby/docs/ref/rrefsqlj81859.html.
DJD> > 
DJD> > I think it would be desirable if the parser recognized it and gave a suitable
DJD> > message, though.
DJD> 
DJD> Not sure it's the job of Derby to recognize syntax it does not
DJD> support/implement. How far would you take it, complete SQL standard, any
DJD> other common SQL?
DJD> (ALTER TABLE is probably not covered by the standard)

It  is covered, even in SQL-92, but I agree covering the full
standard in the parser is quite a task and probably not worth the
effort. Would you recommend that we only recommend the syntax we do
support at any one time?  I notice we do throw a few
SQLState.NOT_IMPLEMENTED exceptions in the parser today, mainly
related to national character set. Are there some guidelines which
specify which "not implemented" syntax is currently recognized, but
rejected?

I think incrementally adding parser recognition with "not implemented"
messages might improve usability even if it were not complete (by some
measure).

I would not put it high on my list of priorities, though ;)

Dag

DJD> 
DJD> Dan.
DJD> 
DJD> 
-- 
Dag H. Wanvik
Sun Microsystems, Web Services, Database Technology Group
Haakon VII gt. 7b, N-7485 Trondheim, Norway
Tel: x43496/+47 73842196, Fax:  +47 73842101

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