public String getTableSQL(String xmlString) {
   try {
     xmlDoc = xmlCon.toXMLDocument(xmlString);
     String sqlString = "";
     sqlString += getSelectStr("all");
     sqlString += getFromStr();
     sqlString += getWhereStr("", "all");
     sqlString += getGroupByStr("all");
     sqlString += getOrderByStr("all");
     sqlString += getLimitStr();
     return sqlString;
   } catch (Exception e) {
     log.error("exception in getTableSQL():\n", e);
     e.printStackTrace();
   }
   return null;
 }