Oracle Database 21c has been released with several new features.   This includes Blockchain tables, which is a new type of table that only allows  insert operations. Other enhancements include a new JSON data type and new SQL Function JSON_TRANSFORM.  Oracle has also updated its Database Administrator’s Guide and JSON Developer’s Guide for this database version.

More information about these new features of Oracle Database 21c at its online  documentation site.

Oracle also has a free cloud tier option as well as a free entry-level training program: Oracle Learning Explorer.