2 files changed, 16 insertions, 1 deletions
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 87104f0d13..f021d571e9 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -25,7 +25,7 @@ from django.db.models.sql.constants import (QUERY_TERMS, ORDER_DIR, SINGLE,
 from django.db.models.sql.datastructures import EmptyResultSet, Empty, MultiJoin
 from django.db.models.sql.expressions import SQLEvaluator
 from django.db.models.sql.where import (WhereNode, Constraint, EverythingNode,
-    ExtraWhere, AND, OR)
+    ExtraWhere, AND, OR, EmptyWhere)
 from django.core.exceptions import FieldError
 
 __all__ = ['Query', 'RawQuery']
@@ -1511,6 +1511,13 @@ class Query(object):
             self.add_filter(('%s__isnull' % trimmed_prefix, False), negate=True,
                     can_reuse=can_reuse)
 
+    def set_empty(self):
+        self.where = EmptyWhere()
+        self.having = EmptyWhere()
+
+    def is_empty(self):
+        return isinstance(self.where, EmptyWhere) or isinstance(self.having, EmptyWhere)
+
     def set_limits(self, low=None, high=None):
         """
         Adjusts the limits on the rows retrieved. We use low/high to set these,
diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index 47f4ffaba9..02847b1f54 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -272,6 +272,14 @@ class WhereNode(tree.Node):
                 if hasattr(child[3], 'relabel_aliases'):
                     child[3].relabel_aliases(change_map)
 
+class EmptyWhere(WhereNode):
+
+    def add(self, data, connector):
+        return
+
+    def as_sql(self, qn=None, connection=None):
+        raise EmptyResultSet
+
 class EverythingNode(object):
     """
     A node that matches everything.