Re: What is the logic of storing XML in a Database?

On 2007-03-30, Cimode <cimode_at_hotmail.com> wrote:

>> If all database systems had a standard interface to do that with then we
>> could just connect the databases together and move data around.
>>
>> In fact there are already two systems that do that. One is XML, the other is
>> ODBC. I understand that ODBC uses a primitive dialect of SQL to select data
>> for transmission. If it could be replaced by a better language then it might
>> be usable.

> I am curious about this statement.  More than 4 ou of 5 dbms's (namely
> ORACLE, DB2, SQL Server) can perfectly communicate db to db using
> ODBC, OLE DB or Native providers.  Why exactly would XML be necessary
> on all of them because one out of 5 minor technologies do not use
> XML?  Is there any *good reason* XML is necessary?

I'm not sure that I would consider ODBC to be perfect. It can certainly transfer data and so could replace simple CSV formats. But XML can also incorporate information about constraints and relationships, I don't believe ODBC can. If ODBC or similar can handle the communication then it's probably preferable to XML. But as I said, I think it needs a more capable language than the one used on ODBC.

There is a database dump format that exports the database structure and data in the form of a single SQL command that can create it. If that only included standards-compliant SQL then it would be a better transfer mediam than eiher ODBC or XML. But if it contains code that isn't executable in a different SQL dialect its capabilities are more limited.

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