-- Some SYS_CONTEXT values
SELECT
  SYS_CONTEXT('USERENV','DB_NAME')              db_name,
  SYS_CONTEXT('USERENV','DB_UNIQUE_NAME')       db_unique_name, 
  SYS_CONTEXT('USERENV','INSTANCE')             instance,
  SYS_CONTEXT('USERENV','INSTANCE_NAME')        instance_name,
  SYS_CONTEXT('USERENV','DATABASE_ROLE')        db_role,
  SYS_CONTEXT('USERENV','SERVICE_NAME')         service_name,
  SYS_CONTEXT('USERENV','LANGUAGE')             language,
  SYS_CONTEXT('USERENV','HOST')                 CLIENT_host,
  SYS_CONTEXT('USERENV','SESSION_USER')         session_user,
  SYS_CONTEXT('USERENV','OS_USER')              os_user,
  SYS_CONTEXT('USERENV','SERVER_HOST')          server_host,
  SYS_CONTEXT('USERENV','NETWORK_PROTOCOL')     network_protocol,  
  SYS_CONTEXT('USERENV','IP_ADDRESS')           ip_address,
  SYS_CONTEXT('USERENV','NLS_DATE_FORMAT')      nls_date_format,
  SYS_CONTEXT('USERENV','NLS_CURRENCY')         nls_currency,
  SYS_CONTEXT('USERENV','NLS_SORT')             nls_sort,
  SYS_CONTEXT('USERENV','NLS_TERRITORY')        nls_territory,
  SYS_CONTEXT('USERENV','MODULE')               application,
  SYS_CONTEXT('USERENV','TERMINAL')             terminal,
  SYS_CONTEXT('USERENV','CURRENT_SCHEMA')       current_schema,
  SYS_CONTEXT('USERENV','CURRENT_SCHEMAID')     current_schemaid,
  SYS_CONTEXT('USERENV','SESSIONID')            sessionid,
  SYS_CONTEXT('USERENV','SID')                  sid,
  SYS_CONTEXT('USERENV','ENTERPRISE_IDENTITY')  enterprise_id,
  SYS_CONTEXT('USERENV','POLICY_INVOKER')       policy_invoker,
  SYS_CONTEXT('USERENV','CURRENT_SQL')          current_sql
FROM DUAL;