diff -r b1243a329b5d -r d53762ae5961 server/sources/rql2sql.py
--- a/server/sources/rql2sql.py	Fri Feb 17 14:41:28 2012 +0100
+++ b/server/sources/rql2sql.py	Mon Feb 20 11:32:06 2012 +0100
@@ -1454,6 +1454,8 @@
         lhs, rhs = mexpr.get_parts()
         # check for string concatenation
         operator = mexpr.operator
+        if operator == '%':
+            operator = '%%'
         try:
             if mexpr.operator == '+' and mexpr.get_type(self._state.solution, self._args) == 'String':
                 return '(%s)' % self.dbhelper.sql_concat_string(lhs.accept(self),