[sf-perl] Some well-formed XML?
ASIGMUND at altera.com
Thu Sep 22 09:42:49 PDT 2005
>> Are XML parsers going to treat (2) any differently from (3), though?
Good question. I'm more a database guy than an XML guy.
Those examples were from my "alternate" solution. I still believe that the best (only?) solution involves something external to the value itself to tell you that no value exists (that is, is NULL), and that attempts to kludge some sort of flag value to tell you whether or not the value actually exists (is NULL or not) is akin to inserting a Hydra's head into the design.
Examples (for the original proposal):
ColumnB is not NULL and not an empty string:
ColumnB is not NULL, but an empty string:
ColumnB is NULL:
>> Also, what about data types which don't support zero-length-strings
>> (ZLS), like dates?
I'm not sure I understand the question. (Perhaps due to my naïve understanding of XML.) In (modern) databases, a column of any data-type should be NULLable. The parser should attempt to decode (or encode) the value string enclosed by <Value></Value> only when IsNULL is FALSE.
From: sanfrancisco-pm-bounces at pm.org [mailto:sanfrancisco-pm-bounces at pm.org] On Behalf Of Josh Berkus
Sent: Thursday, September 22, 2005 09:11
To: San Francisco Perl Mongers User Group
Subject: Re: [sf-perl] Some well-formed XML?
> ColumnB is not null and not empty:
> ColumnB is not null, but is an empty string:
> ColumnB is null:
Are XML parsers going to treat (2) any differently from (3), though?
That is, if I hand an XML application (2), might it return (3) instead
Also, what about data types which don't support zero-length-strings
(ZLS), like dates?
My general inclination would be to treat all ZLS as NULLs in the
database, unless I have a specific reason to do otherwise or unless the
value is defined as "required" in the DTD.
Anyway, this is *terrific* food for thought. BTW, what was the name of
the CPAN module for SQL-->XML conversion which was demoed at SFPerl
abotu 6months ago?
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