把datatable里的数据转换成xml格式的字符串

string GetXmlByDataTable()
    {
        string xmlstr;
        string sql = "select top 10 * from BasicInfo";
        DataTable dt = idb.ReturnDataTable(sql);
        dt.TableName = "tbname";
        if (dt.Rows.Count>0)
        {
            System.IO.StringWriter writer = new System.IO.StringWriter();
            dt.WriteXml(writer);
            xmlstr = writer.ToString();
        }
        return xmlstr;
    }