join two table using Linq

   var quaryFirst = from RecordId in dtXMLFILE3.AsEnumerable()
                                 join rowId in dtXMLFILE4.AsEnumerable()
               on RecordId.Field<int>("ColumnName") equals rowId.Field<int>("ColumnName")
                                 join policy in dtXMLFILE5.AsEnumerable()
               on rowId.Field<int>("ColumnName") equals policy.Field<int>("ColumnName")
                                 select new
                                 {
                                     Id = RecordId.Field<int>("ColumnName"),
                                     rId = rowId.Field<int>("ColumnName"),
                                     rr_Id = rowId.Field<int>("ColumnName"),
                                     source = rowId.Field<string>("ColumnName"),
                                     count = rowId.Field<string>("ColumnName"),
                                     dis = policy.Field<string>("ColumnName"),
                                     dm = policy.Field<string>("ColumnName"),
                                     sp = policy.Field<string>("ColumnName"),
                                     Poli = policy.Field<int>("ColumnName")
                                 };