[pull] main from django:main

django/db/backends/oracle/features.py

@@ -86,9 +86,6 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "annotations.tests.NonAggregateAnnotationTestCase.test_custom_functions",
         "annotations.tests.NonAggregateAnnotationTestCase."
         "test_custom_functions_can_ref_other_functions",
-        # A bug in Django with respect to unioning ordered querysets (#36938).
-        "queries.test_qs_combinators.QuerySetSetOperationTests."
-        "test_count_union_with_select_related_in_values",
     }
     insert_test_table_with_defaults = (
         "INSERT INTO {} VALUES (DEFAULT, DEFAULT, DEFAULT)"

django/db/models/sql/compiler.py

@@ -590,10 +590,6 @@ def get_combinator_sql(self, combinator, all):
                     raise DatabaseError(
                         "LIMIT/OFFSET not allowed in subqueries of compound statements."
                     )
-                if compiler.get_order_by():
-                    raise DatabaseError(
-                        "ORDER BY not allowed in subqueries of compound statements."
-                    )
         parts = []
         empty_compiler = None
         for compiler in compilers:
@@ -640,6 +636,15 @@ def _get_combinator_part_sql(self, compiler):
         if selected is not None and compiler.query.selected is None:
             compiler.query = compiler.query.clone()
             compiler.query.set_values(selected)
+        if (
+            (
+                features.requires_compound_order_by_subquery
+                and not features.ignores_unnecessary_order_by_in_subqueries
+            )
+            or not features.supports_parentheses_in_compound
+        ) and compiler.get_order_by():
+            compiler.query = compiler.query.clone()
+            compiler.query.clear_ordering(force=False)
         part_sql, part_args = compiler.as_sql(with_col_aliases=True)
         if compiler.query.combinator:
             # Wrap in a subquery if wrapping in parentheses isn't

tests/queries/test_qs_combinators.py

@@ -419,7 +419,6 @@ def test_union_with_select_related_and_order(self):
         qs2 = base_qs.filter(name="a2")
         self.assertSequenceEqual(qs1.union(qs2).order_by("pk"), [a1, a2])
 
-    @skipUnlessDBFeature("supports_slicing_ordering_in_compound")
     def test_union_with_select_related_and_first(self):
         e1 = ExtraInfo.objects.create(value=7, info="e1")
         a1 = Author.objects.create(name="a1", num=1, extra=e1)
@@ -570,7 +569,6 @@ def test_union_in_subquery_related_outerref(self):
         # Combined queries don't mutate.
         self.assertCountEqual(qs, ["a1", "a2"])
 
-    @skipUnlessDBFeature("supports_slicing_ordering_in_compound")
     def test_union_in_with_ordering(self):
         qs1 = Number.objects.filter(num__gt=7).order_by("num")
         qs2 = Number.objects.filter(num__lt=2).order_by("num")
@@ -607,7 +605,6 @@ def test_count_union_with_select_related(self):
         qs = Author.objects.select_related("extra").order_by()
         self.assertEqual(qs.union(qs).count(), 1)
 
-    @skipUnlessDBFeature("supports_slicing_ordering_in_compound")
     def test_count_union_with_select_related_in_values(self):
         e1 = ExtraInfo.objects.create(value=1, info="e1")
         a1 = Author.objects.create(name="a1", num=1, extra=e1)
@@ -692,11 +689,9 @@ def test_unsupported_ordering_slicing_raises_db_error(self):
         msg = "LIMIT/OFFSET not allowed in subqueries of compound statements"
         with self.assertRaisesMessage(DatabaseError, msg):
             list(qs1.union(qs2[:10]))
-        msg = "ORDER BY not allowed in subqueries of compound statements"
-        with self.assertRaisesMessage(DatabaseError, msg):
-            list(qs1.order_by("id").union(qs2))
-        with self.assertRaisesMessage(DatabaseError, msg):
-            list(qs1.union(qs2).order_by("id").union(qs3))
+        # Unioning ordered queries is permitted.
+        list(qs1.order_by("id").union(qs2))
+        list(qs1.union(qs2).order_by("id").union(qs3))
 
     @skipIfDBFeature("supports_select_intersection")
     def test_unsupported_intersection_raises_db_error(self):