          return self.date_extract_sql(lookup_type, field_name)
  
      def datetime_trunc_sql(self, lookup_type, field_name, tzname):
          field_name = self._convert_field_to_tz(field_name, tzname)
          # https://docs.oracle.com/database/121/SQLRF/functions271.htm#SQLRF52058
          if lookup_type in ('year', 'month'):
              sql = "TRUNC(%s, '%s')" % (field_name, lookup_type.upper())
          elif lookup_type == 'quarter':
              sql = "TRUNC(%s, 'Q')" % field_name
          elif lookup_type == 'week':
 
</s> remove         # https://docs.oracle.com/database/121/SQLRF/functions271.htm#SQLRF52058
 </s> add         # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf/ROUND-and-TRUNC-Date-Functions.html </s> remove             # https://docs.oracle.com/database/121/SQLRF/functions067.htm#SQLRF00639
 </s> add             # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf/EXTRACT-datetime.html </s> remove         # https://docs.oracle.com/database/121/SQLRF/sql_elements002.htm#SQLRF51054
 </s> add         # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf
        # /Data-Type-Comparison-Rules.html#GUID-D0C5A47E-6F93-4C2D-9E49-4F2B86B359DD </s> remove .. [#fnsdorelate] *See* `SDO_RELATE documentation <https://docs.oracle.com/database/121/SPATL/sdo_relate.htm#SPATL1039>`_, from the Oracle Spatial and Graph Developer's Guide.
 </s> add .. [#fnsdorelate] *See* `SDO_RELATE documentation <https://docs.oracle.com/en/
   database/oracle/oracle-database/18/spatl/spatial-operators-reference.html#
   GUID-97C17C18-F05E-49B4-BE11-E89B972E2A02>`_, from the Oracle Spatial and
   Graph Developer's Guide. </s> remove   columns`_.

  .. _`identity columns`: https://docs.oracle.com/database/121/DRDAA/migr_tools_feat.htm#DRDAA109
 </s> add   columns <https://docs.oracle.com/en/database/oracle/oracle-database/18/drdaa/
  intro-to-tools-and-products-supporting-migraiton.html#GUID-14E4817B-F3BC-4D99
  -B471-A0ACDC303CC9>`__.
        # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf/ROUND-and-TRUNC-Date-Functions.html
          return self.date_extract_sql(lookup_type, field_name)
  
      def datetime_trunc_sql(self, lookup_type, field_name, tzname):
          field_name = self._convert_field_to_tz(field_name, tzname)
        # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf/ROUND-and-TRUNC-Date-Functions.html
          if lookup_type in ('year', 'month'):
              sql = "TRUNC(%s, '%s')" % (field_name, lookup_type.upper())
          elif lookup_type == 'quarter':
              sql = "TRUNC(%s, 'Q')" % field_name
          elif lookup_type == 'week':
keep keep keep keep replace keep keep keep keep keep
 Updated Oracle docs links to Oracle 18c. 
django/db/backends/oracle/operations.py