Search notes:

Oracle: V$VERSION

select
   banner      -- 'Oracle%' or 'Personal Oracle%' or 'Oracle %Perf%' or …
   banner_full,
   regexp_replace(banner_full, '.*\n(.*)', '\1') banner_full_2nd_line,
   banner_legacy,
   con_id
from
   v$version;

See also

The view PRODUCT_COMPONENT_VERSION selects from v$version.
dbms_utility.db_version
$ORACLE_HOME/bin/oraversion
Oracle Dynamic Performance Views
Determine database versions

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