          new_temp_field.column = self._generate_temp_name(new_field.column)
          # Add it
          self.add_field(model, new_temp_field)
          # Explicit data type conversion
          # https://docs.oracle.com/database/121/SQLRF/sql_elements002.htm#SQLRF51054
          new_value = self.quote_name(old_field.column)
          old_type = old_field.db_type(self.connection)
          if re.match('^N?CLOB', old_type):
              new_value = "TO_CHAR(%s)" % new_value
              old_type = 'VARCHAR2'
 
</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 .. [#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             # 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/functions271.htm#SQLRF52058
 </s> add         # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf/ROUND-and-TRUNC-Date-Functions.html </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
        # /Data-Type-Comparison-Rules.html#GUID-D0C5A47E-6F93-4C2D-9E49-4F2B86B359DD
          new_temp_field.column = self._generate_temp_name(new_field.column)
          # Add it
          self.add_field(model, new_temp_field)
          # Explicit data type conversion
        # https://docs.oracle.com/en/database/oracle/oracle-database/18/sqlrf
        # /Data-Type-Comparison-Rules.html#GUID-D0C5A47E-6F93-4C2D-9E49-4F2B86B359DD
          new_value = self.quote_name(old_field.column)
          old_type = old_field.db_type(self.connection)
          if re.match('^N?CLOB', old_type):
              new_value = "TO_CHAR(%s)" % new_value
              old_type = 'VARCHAR2'
keep keep keep keep replace keep keep keep keep keep
 Updated Oracle docs links to Oracle 18c. 
django/db/backends/oracle/schema.py