MySQL Writes Exception for PHP in License
ryanjensen writes "According to an article on News.com, MySQL wrote an exception into its license to allow PHP to use its libraries. From the article: 'Because MySQL owns copyright to all the MySQL code, it can include additional license provisions to its software. The new provision, called the Free and Open Source Software License Exception, enables people to use MySQL client libraries with other open-source projects under other open-source licenses other than the GPL.'"
Go figure...
The MySQL extension has been debundled because MySQL has changed its licensing policy and, effective 4.0, the library is now distributed either under the GPL (which is incompatible with the PHP license) or by purchasing a commercial license. You can still link to the MySQL library by downloading it separately from PHP, installing it and the configuring PHP to point to it. This will work both with 3.x and 4.x. However, technically you can't link against 4.x unless you have a commercial license from MySQL.