diff --git a/process/Sql_lib/process.js b/process/Sql_lib/process.js
index 97349505c724ec2fa47c9315e6a33f7c6078fb1b..96fad8157daf52446aaf45d30932f3e1e99568d7 100644
--- a/process/Sql_lib/process.js
+++ b/process/Sql_lib/process.js
@@ -851,8 +851,8 @@ SqlBuilder.prototype._getClause = function (pElement, pPrefix, pAutoJoin)
             pElement = _getElement(pElement);
         }
     }
-    
-    if (pPrefix)
+
+    if (pPrefix && pElement)
         pElement = pPrefix + " " + pElement;
     
     return [pElement.toString(), preparedValues];