The function returns the URL of the XML Types associate XML schema. This applies only to schema based instances. It will return NULL for non-schema based types.
The function returns string.
The call of XMLType constructor creates an schema-based instance and getSchemaURL() returns the specified URL
select XMLType('<sample />', 'file://xmlschema/test0001/clean.xsd').getSchemaURL() callret VARCHAR _______________________________________________________________________________ file://xmlschema/test0001/clean.xsd 1 Rows. -- 00000 msec.