使用XDocument从集合生成XML

我有一个下的实体

class DBDetails
    {
        public int ServerId { get; set; }
        public string Title { get; set; }
        public string Address { get; set; }
        public int DBId { get; set; }
        public string DbName { get; set; }
        public string UserId { get; set; }
        public string Password { get; set; }
    }

按照填充

List<DBDetails> lstDBDetails = new List<DBDetails>();
lstDBDetails.Add(new DBDetails { ServerId = 1, Title = "IISDevdb1", Address = "Address1", DBId = 1, DbName = "db1", UserId = "u1", Password = "p1" });
lstDBDetails.Add(new DBDetails { ServerId = 2, Title = "iis2", Address = "Address2", DBId = 2, DbName = "db2", UserId = "u2", Password = "p2" });
lstDBDetails.Add(new DBDetails { ServerId = 1, Title = "IISDevdb1", Address = "Address1", DBId = 3, DbName = "db3", UserId = "u3", Password = "p3" });

我需要从它生成以下xml

<DataBaseServers>
  <DataBaseServer id="1" title="IISDevdb1" address="Address1">
    <DataBases>      
      <database id="1" name="db1" userID="u1" password="p1" />
      <database id="3" name="db3" userID="u3" password="p3" />
    </DataBases>
  </DataBaseServer>
  <DataBaseServer id="2" title="iis2" address="Address2">
  <DataBases>      
      <database id="1" name="db2" userID="u2" password="p2" />    
    </DataBases>
</DataBaseServers>

如何使用XDocument完成此操作？

我的射击失败

var res = (from x in lstDBDetails
                       group x by x.ServerId into g
                       select new
                       {
                           A = g.Key ,
                           B = g.ToList()
                       });
            var doc = new XDocument(
                new XElement("DataBaseServers",
                    res.Select(x =>
                        new XElement("DataBaseServer",
                             new XAttribute("id", x.A),                             
                                 new XElement("DataBases",
                                     x.B.Select(y =>
                                     new XElement("database",
                                         new XAttribute("id", y.DBId),
                                         new XAttribute("name", y.DbName),
                                         new XAttribute("userID", y.UserId),
                                         new XAttribute("password", y.Password))))))));

var res = (from x in lstDBDetails
                       group x by new { x.ServerId, x.Title,x.Address } into g
                       select new
                       {
                           ServerId = g.Key.ServerId,
                           Title = g.Key.Title,
                           Address = g.Key.Address,
                           B = g.ToList()
                       });
            var doc = new XDocument(
                new XElement("DataBaseServers",
                    res.Select(x =>
                        new XElement("DataBaseServer",
                             new XAttribute("id", x.ServerId),
                             new XAttribute("title", x.Title),
                             new XAttribute("address", x.Address),
                                 new XElement("DataBases",
                                     x.B.Select(y =>
                                     new XElement("database",
                                         new XAttribute("id", y.DBId),
                                         new XAttribute("name", y.DbName),
                                         new XAttribute("userID", y.UserId),
                                         new XAttribute("password", y.Password))))))));