diff --git a/django/db/backends/oracle/operations.py b/django/db/backends/oracle/operations.py
index b0b50f7868..a712442f6e 100644
--- a/django/db/backends/oracle/operations.py
+++ b/django/db/backends/oracle/operations.py
@@ -253,6 +253,7 @@ END;
         return " DEFERRABLE INITIALLY DEFERRED"
 
     def fetch_returned_insert_columns(self, cursor, returning_params):
+        columns = []
         for param in returning_params:
             value = param.get_value()
             if value is None or value == []:
@@ -264,7 +265,8 @@ END;
                     'https://code.djangoproject.com/ticket/28859).'
                 )
             # cx_Oracle < 7 returns value, >= 7 returns list with single value.
-            yield value[0] if isinstance(value, list) else value
+            columns.append(value[0] if isinstance(value, list) else value)
+        return tuple(columns)
 
     def field_cast_sql(self, db_type, internal_type):
         if db_type and db_type.endswith('LOB'):
diff --git a/django/db/models/base.py b/django/db/models/base.py
index b2a60629c9..919371540d 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -889,8 +889,9 @@ class Model(metaclass=ModelBase):
 
             returning_fields = meta.db_returning_fields
             results = self._do_insert(cls._base_manager, using, fields, returning_fields, raw)
-            for result, field in zip(results, returning_fields):
-                setattr(self, field.attname, result)
+            if results:
+                for value, field in zip(results[0], returning_fields):
+                    setattr(self, field.attname, value)
         return updated
 
     def _do_update(self, base_qs, using, pk_val, values, update_fields, forced_update):
diff --git a/django/db/models/query.py b/django/db/models/query.py
index 5fdee3ff37..1fa7a318c8 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -1249,15 +1249,11 @@ class QuerySet:
         bulk_return = connections[self.db].features.can_return_rows_from_bulk_insert
         for item in [objs[i:i + batch_size] for i in range(0, len(objs), batch_size)]:
             if bulk_return and not ignore_conflicts:
-                inserted_columns = self._insert(
+                inserted_rows.extend(self._insert(
                     item, fields=fields, using=self.db,
                     returning_fields=self.model._meta.db_returning_fields,
                     ignore_conflicts=ignore_conflicts,
-                )
-                if isinstance(inserted_columns, list):
-                    inserted_rows.extend(inserted_columns)
-                else:
-                    inserted_rows.append(inserted_columns)
+                ))
             else:
                 self._insert(item, fields=fields, using=self.db, ignore_conflicts=ignore_conflicts)
         return inserted_rows
diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 63ca817355..9433540d7c 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -1385,10 +1385,10 @@ class SQLInsertCompiler(SQLCompiler):
                 return self.connection.ops.fetch_returned_insert_rows(cursor)
             if self.connection.features.can_return_columns_from_insert:
                 assert len(self.query.objs) == 1
-                return self.connection.ops.fetch_returned_insert_columns(cursor, self.returning_params)
-            return [self.connection.ops.last_insert_id(
+                return [self.connection.ops.fetch_returned_insert_columns(cursor, self.returning_params)]
+            return [(self.connection.ops.last_insert_id(
                 cursor, self.query.get_meta().db_table, self.query.get_meta().pk.column
-            )]
+            ),)]
 
 
 class SQLDeleteCompiler(SQLCompiler):