diff -r df44d7163582 -r e3994fcc21c3 server/sources/rql2sql.py
--- a/server/sources/rql2sql.py	Tue Sep 21 16:35:37 2010 +0200
+++ b/server/sources/rql2sql.py	Thu Sep 23 23:28:58 2010 +0200
@@ -761,6 +761,8 @@
             restrictions.append(restriction)
         restriction = ' AND '.join(restrictions)
         if not restriction:
+            if tables:
+                return 'SELECT 1 FROM %s' % ', '.join(tables)
             return ''
         if not tables:
             # XXX could leave surrounding EXISTS() in this case no?
@@ -1141,11 +1143,11 @@
 
     def visit_constant(self, constant):
         """generate SQL name for a constant"""
-        value = constant.value
         if constant.type is None:
             return 'NULL'
+        value = constant.value
         if constant.type == 'Int' and  isinstance(constant.parent, SortTerm):
-            return constant.value
+            return value
         if constant.type in ('Date', 'Datetime'):
             rel = constant.relation()
             if rel is not None:
@@ -1158,7 +1160,7 @@
                 # we may found constant from simplified var in varmap
                 return self._mapped_term(constant, '%%(%s)s' % value)[0]
             except KeyError:
-                _id = constant.value
+                _id = value
                 if isinstance(_id, unicode):
                     _id = _id.encode()
         else: