The Library is currently in the process of being upgraded from Oracle Database Version 22.214.171.124 to 126.96.36.199.
Demos are being upgraded to reflect the new Container paradigm as well as EBR (Edition Based Redefinition) and may contain references to CDBs, PDBs,
and other objects you may not be familiar with such as CDB_OBJECTS_AE: Welcome to 12c.
Have you viewed the Library's main Table of Contents? If not ... [Click Here]
... scroll down the page and you will find links to the largest collection of Oracle Database demos on the net.