Index: lib/dmllib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/dmllib.php,v
retrieving revision 1.116.2.33
diff -u -r1.116.2.33 dmllib.php
--- lib/dmllib.php	26 Sep 2009 11:55:57 -0000	1.116.2.33
+++ lib/dmllib.php	7 Jan 2010 12:14:55 -0000
@@ -1899,7 +1899,9 @@
             break;
     }
 
-    return ' ' . $sql . ' '; /// Adding spaces to avoid wrong SQLs due to concatenation
+    // Add spaces to avoid wrong SQLs due to concatenation.
+    // Add brackets to avoid operator precedence problems.
+    return ' (' . $sql . ') ';
 }
 
 /**