GPL linking question

[Hamish Moffatt <hamish@debian.org>]

Hi all,

A question about linking non-free programs to GPL; specifically, about
what 'linking' specifically means. I'm specifically referring to a
(hypothetical) program which requires the mysql server.

The mysql server is GPL. The proprietary program implements its own
mysql client to connect to the server; it doesn't link against the
mysql client code (which is also GPL).

The mysql.com web site says you require a commercial license for the
mysql server (ie you cannot use it under the GPL) if (among other reasons):

"You have a commercial application that ONLY works with MySQL and ships 
the application with the MySQL server. This is because we view this as 
linking even if it is done over the network."

Is that a fair definition of linking? 
(Note that the above clause is only on the web site, and isn't actually
added to the GPL they use for the mysql server software itself.)

The GPL FAQ seems to imply that if you keep the proprietary and
GPL components at "arm's length", like a compiler and the kernel,
or an editor and the shell, that's OK. See
http://www.gnu.org/copyleft/gpl-faq.html#GPLInProprietarySystem

What if the application bundled MySQL but could also connect to other
SQL servers, such as Oracle or MS SQL?

thanks
Hamish
-- 
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>