Because Oracle is constantly developing the Oracle database and these versions may also require maintenance, Oracle periodically produces new versions.

The Oracle database version is classified into five numeric sections that indicate a summary of the information.

To find out your current version, you can query the data through the PRODUCT_COMPONENT_VERSION dictionary.

SELECT * FROM PRODUCT_COMPONENT_VERSION;

About Oracle Database Release Numbers:

As mentioned earlier, the Oracle database version is classified into five numeric sections, for example (19.0.0.0.0), and Oracle releases are issued in (version & version_full).

Where the Version is assigned to the major release version, and the major release depends on the last two digits of the year in which the release was first produced, for example, the first version that was released for the Oracle database for the first time in 2018 is 18, so the version is 18.0.0.0.0

As for version_full, it is considered an update to the version and is determined on the basis of the version in addition to the quarterly updates (Update) and also the quarterly update review (Revision).

The version_full is classified by five numerical parts separated by dots as shown below:

Major database release number: This number indicates the major release version. This is also indicated by the last two digits of the year in which the Oracle Database was first released.

Release Update version: This number indicates the release update version (Update).

Release Update Revision version: This number indicates the release update revision version (Revision).

Increment version: This number indicates the cumulative version.

Release Update Revision version: This section is reserved for future use.

Oracle strongly recommends that you perform updates and revisions before upgrading.

It is also worth noting that starting with Oracle 18c, Oracle has started providing quarterly updates known as release updates and also release revisions, and Oracle no longer issues Patch sets, for more details you can visit the Oracle Support Note 2285040.1.