infopath 数据在代码里插入重复节,该怎么解决

     XPathNavigator domNav = MainDataSource.CreateNavigator();                        XPathNodeIterator rows = domNav.Select("/my:myFields/my:qj_detail", NamespaceManager);                        string inQjDetailSql = string.Empty;                       //保存请假详细信息                        while (rows.MoveNext())                        {                            string beginDate = rows.Current.SelectSingleNode("my:beginDate", NamespaceManager).Value.ToString();                            string endDate = rows.Current.SelectSingleNode("my:endDate", NamespaceManager).Value.ToString();                            string reson = rows.Current.SelectSingleNode("my:reson", NamespaceManager).Value.ToString();                            string note = rows.Current.SelectSingleNode("my:note", NamespaceManager).Value.ToString();                            inQjDetailSql += "INSERT INTO qingjia_detail (qj_id,Begin_Date,End_Date,Style,Note)";                            inQjDetailSql += " VALUES ('" + qj_id + "','" + beginDate + "','" + endDate + "','" + reson + "','" + note + "');";                        }