Fixed #18414 -- qs.exists() for sliced distinct queries

django/db/models/sql/query.py

@@ -431,7 +431,8 @@ class Query(object):
 
     def has_results(self, using):
         q = self.clone()
-        q.clear_select_clause()
+        if not q.distinct:
+            q.clear_select_clause()
         q.clear_ordering(True)
         q.set_limits(high=1)
         compiler = q.get_compiler(using=using)

tests/queries/tests.py

@@ -1856,6 +1856,25 @@ class ExistsSql(TestCase):
         id, name = connection.ops.quote_name('id'), connection.ops.quote_name('name')
         self.assertTrue(id not in qstr and name not in qstr)
 
+    def test_ticket_18414(self):
+        Article.objects.create(name='one', created=datetime.datetime.now())
+        Article.objects.create(name='one', created=datetime.datetime.now())
+        Article.objects.create(name='two', created=datetime.datetime.now())
+        self.assertTrue(Article.objects.exists())
+        self.assertTrue(Article.objects.distinct().exists())
+        self.assertTrue(Article.objects.distinct()[1:3].exists())
+        self.assertFalse(Article.objects.distinct()[1:1].exists())
+
+    @unittest.skipUnless(connection.features.can_distinct_on_fields,
+                         'Uses distinct(fields)')
+    def test_ticket_18414_distinct_on(self):
+        Article.objects.create(name='one', created=datetime.datetime.now())
+        Article.objects.create(name='one', created=datetime.datetime.now())
+        Article.objects.create(name='two', created=datetime.datetime.now())
+        self.assertTrue(Article.objects.distinct('name').exists())
+        self.assertTrue(Article.objects.distinct('name')[1:2].exists())
+        self.assertFalse(Article.objects.distinct('name')[2:3].exists())
+
 
 class QuerysetOrderedTests(unittest.TestCase):
     """