Another similar and very common case is to provide libraries with the interpreter which are themselves interpreted. For instance, Perl comes with many Perl modules, and a Java implementation comes with many Java classes. These libraries and the programs that call them are always dynamically linked together.

A consequence is that if you choose to use GPL'd Perl modules or Java classes in your program, you must release the program in a GPL-compatible way, regardless of the license used in the Perl or Java interpreter that the combined Perl or Java program will run on.

DBI and Class::DBI are both released under GPL or the Artistic License. In which case the application to be interpreted by perl is not by definition required to be GPL.

Additionally, unless the aplication uses specific Mysql only features, the use of DBI or Class::DBI in the aplication does not limited it to mysql only, which would invalidate this discussion wether or not one is required to release the written perl scripts under GPL.