[SQL] Oracle pass namespace parameter to EXTRACT and EXTRACTVALUE XML functions

When working with Oracle's EXTRACT and EXTRACTVALUE XML functions, you'll have the option to add a namespace (namespace_string) parameter, but unfortunately the official documentation is very thin on that part.

Said argument must be a string in the form of:

'xmlns:alias="URI"' or 'xmlns="URI"'

if you need to list multiple namespaces, simply separate them with a space character:

'xmlns:alias="URI" xmlns:alias1="URI1"' 

or 

'xmlns:alias="URI" xmlns="URI1"'