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- From: "Bullard, Claude L (Len)" <clbullar@ingr.com>
- To: xml-dev@XML.ORG
- Date: Mon, 26 Jun 2000 08:11:44 -0500
That was the point. With X-Spy, it opened the
table but as it had no data, did not enable
the schema generator. There may be some magic
command that allows that but I haven't found
it yet.
How would it get foreign key information? While
one does declare primary keys, foreign keys aren't
declared AFAICT in many schema design tools. One
does usually find a description field and if the
designer does a professional job, they may include
the role of the field value in the overall design,
eg, a key to a table named nnnnn.
In any event, how far do people propose a schema
generator can get reverse engineering out of an
instance? It appears to me that critical information
is missing, so while it is an excellent place to
start, I think one still has to tighten up afterwards.
That makes me think that an ideal toolkit provides
both a means to reverse engineer, then an editor for
cleanup and restructuring. BTW, I'm not looking
for ads here because I can find the tools, just noting
some generic features I think one should consider
when making recommendations to companies or individuals
who want to build up their kits.
Len Bullard
Intergraph Public Safety
clbullar@ingr.com
http://fly.hiwaay.net/~cbullard/lensongs.ram
Ekam sat.h, Vipraah bahudhaa vadanti.
Daamyata. Datta. Dayadhvam.h
-----Original Message-----
From: tpassin@home.com [mailto:tpassin@home.com]
Sent: Friday, June 23, 2000 7:57 PM
To: xml-dev@xml.org
Subject: Re: SQL Schema to XML Schema generator [any out there?]
Len Bullard wrote -
> By the way, just as an addendum. When you use
> tools that enable you to generate schemas from
> say, relational dbs, tools that reverse engineer
> instances can only get you so far. For example,
> XML-Spy has a great feature for doing this using
> ODBC to connect and get you the table layouts.
> However, if a table has no data, it can't, of course,
> generate that so it doesn't kick out an instance.
> So when you try to generate a schema, you are stuck.
>
> 1. Use a test database with sufficient data to
> generate the instance. Otherwise, it can't
> do anything for that table.
>
Not necessarily. I haven't tried it with Spy, but ODBC has the ability to
get table definitions from those databases that support them. And even dBase
tables carry schema information within themselves. I **think** it can also
get foreign key information as well, but I'm not as positive on this.
Whether a particular product uses the capability, though, that's another
thing.
Cheers,
Tom Passin
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