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List:       kde-devel
Subject:    Re: ODBC on Linux
From:       Bavo De Ridder <bavo () ace ! ulyssis ! student ! kuleuven ! ac ! be>
Date:       1999-04-08 11:35:03
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On Thu, 08 Apr 1999, Denis Pershin wrote:
>-----BEGIN PGP SIGNED MESSAGE-----
>
>>The main advantage of OLE DB is that you only pay for what you get. If you are
>>accessing a flat file database (a mailbox), you will only load the (small) OLE
>>DB framework and the native text-driver, nothing more.
>>
>>Imagina you could do this in KDE: you have an SQL database with your customers
>>email, addres, .... and a plain mailbox (KMail). With OLE DB you can get a list
>>of al the email-addresses of customers who haven't sended you a mail in the
>>last 4 weeks.
>>
>>Or: OLE DB is *very* different from ODBC and should be considered something new.
>
>Maybe you will explain the difference more detailed?
>


I'll try. First of all: my english is not so good, so please have a look at the
Microsoft site for a more in-depth comparison.

ODBC is nothing more than a generalized native database driver. ODBC mostly
translates calls to the native database driver api language. This means ODBC is
build around databases, connections, ...

OLE DB doesn't assume there is a database. It only assumes there is a
datasource somewhere. This datasource is capable of offering it's data in
rowset form. OLE DB doesn't know anything about connections, ... only about
datasources, sessions and command objects. Al these objects are only interfaces
in COM. CORBA in the KDE case. So anyone who has a datasource (KMail) could
build a library containing implementations of these COM (CORBA) interfaces. You
can even mix two datasources in a query without either datasource knowing the
other. The query language can be different. Depending on the exposed
interfaces, you know what a datasource is capable of:

ICommand *datasourceCommand;

result = dataSourceCommand->QueryInterface("IParameterInfo');

If this returns a valid result, then we know this particular Command object of
a datasource, is capable of parsing and executing queries with parameters. THe
IParameter will let us investigate the different parameters, their type, ...

OLE DB lets you look differently at data in your system. Off course, both ODBC
and OLE DB let you extract data from a database (datasource). But the
difference is in the way you extract data.

Also, thanks to COM (CORBA) OLE DB is very lightweight.


BDR

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