Trying to write LINQ Query to XML or Dataset

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C#

ASP.NET

XML

LINQ

Hi, I am new to LINQ and am struggling to write my data out.
I have 2 sets of incoming data, one from a SQL table the other from an XML file. These I
union using Linq, after doing some comparison between the records.
I then need to write the comparison data to another dataset or direct to XML. Due to the
anonymous nature of the variables I am receiving errors at every turn and am now struggling.
Any advice is appreciated. The code is as follows:

DataSet dsPDADocs = new DataSet();
dsPDADocs.ReadXml(path, XmlReadMode.ReadSchema);
dsPDADocs.AcceptChanges();
conCon.Open();
SqlDataAdapter daDBDocs = new SqlDataAdapter("Select * from Documents (nolock)", conCon);
DataSet dsDBDocs = new DataSet();
daDBDocs.FillSchema(dsDBDocs, SchemaType.Source, "Documents");
daDBDocs.Fill(dsDBDocs, "Documents");
var orig = dsPDADocs.Tables[0].AsEnumerable();
var updated = dsPDADocs.Tables[0].AsEnumerable();
//First, get records to delete if any
var delRec = from u in orig where !(from o in orig
   select o.Field<Guid>("DocumentID"))
   .Contains(u.Field<Guid>(" DocumentID"))
   select new
                         {
                             prim_key = u.Field<Guid>("DocumentID"),
                             field1 = u.Field<Guid>("SourceID"),
                             field2 = u.Field<Guid>("DocumentTypeID"),
                             field3 = u.Field<object>("DocumentSource"),
                             field4 = u.Field<string>("DocumentFilename"),
                             field5 = u.Field<int>("DocumentVersion"),
                             rec_type = "D"//Deleted
                         };
            //Secondly, getting updated records
            var updRec = from o in orig
                         join u in updated
                         on o.Field<Guid>("DocumentID")
                         equals u.Field<Guid>("DocumentID")
                         where (o.Field<Guid>("SourceID") !=
                         u.Field<Guid>("SourceID")) ||
                         (o.Field<int>("DocumentVersion") !=
                         u.Field<int>("DocumentVersion"))
                         select new
                         {
                             prim_key = o.Field<Guid>("DocumentID"),
                             field1 = o.Field<Guid>("SourceID"),
                             field2 = o.Field<Guid>("DocumentTypeID"),
                             field3 = o.Field<object>("DocumentSource"),
                             field4 = o.Field<string>("DocumentFilename"),
                             field5 = o.Field<int>("DocumentVersion"),
                             rec_type = "M"//Mofified
                         };
            //Third get records to add, if any
            var addRec = from o in orig
                         where !(from u in updated
                                 select u.Field<Guid>("DocumentID"))
                         .Contains(o.Field<Guid>(" DocumentID"))
                         select new
                         {
                             prim_key = o.Field<Guid>("DocumentID"),
                             field1 = o.Field<Guid>("SourceID"),
                             field2 = o.Field<Guid>("DocumentTypeID"),
                             field3 = o.Field<object>("DocumentSource"),
                             field4 = o.Field<string>("DocumentFilename"),
                             field5 = o.Field<int>("DocumentVersion"),
                             rec_type = "A"//Added
                         };
            var Union = addRec.Union(updRec).Union(delRec);
            //DataTable dtResults = Union.ToADOTable(rec => new object[] { Union });

            string fileName = "Manifest.xml";
            foreach(MyResult dr in Union)
            //foreach(DataRow dr in dtResults)
            {
                XElement Documents =
                    new XElement("Document",
                    new XElement("DocumentID",dr.DocumentID),
                    new XElement("SourceID", dr.SourceID),
                    new XElement("DocumentTypeID", dr.DocumentTypeID),
                    new XElement("DocumentSource", dr.DocumentSource),
                    new XElement("DocumentFilename", dr.DocumentFilename),
                    new XElement("DocumentVersion", dr.DocumentVersion),
                    new XElement("rec_type", dr.rec_type));
                    Documents.Save(fileName);
            };

The error I am receiving is cannot convert type AnonymousType#1 to My Result on the foreach line