According to the rfc4122 specification, UUID is a 128 bits long identifier used to uniquely identify objects in various applications and systems. Many programming languages gives us ability to generate UUID using API, however Oracle don't provide a function which can do this directly. We need to use some other indirect solutions:
1. Using sys_guid function
Oracle provide a function called sys_guid() which generates unique identifiers and it can be used, with a simple modification, to generate UUIDs.
Now we can can use regexp_replace and rawtohex function to generate random UUID.
2. Using Java based function
Another method to generate unique indentifiers in Oracle is to use Java based function that will generate UUIDs using java.util API.
3. Using dbms_crypto and utl_raw functions
To use dbms_crypto function you will need to grant special permissions to your database user: