C# Linq多列合并解决办法

C# Linq多列合并

using (WcfDataEntities DbContext = new WcfDataEntities())
                {
                    var listFields = from a in DbContext.ObjectList
                                     join b in DbContext.FieldList
                                     on a.AutoID equals b.ParentRowID
                                     where a.ObjectName == strTableName && a.ObjectType == "T"
                                     orderby b.Sort
                                     select new MessageInfo
                                     {
                                         AutoID = b.AutoID,
                                        FieldName = b.FieldName + '|' + b.DataType,
                                         FieldNameCh = b.FieldNameCh

                                     };
                    var listMessage = listFields.ToList<MessageInfo>();
                    strJsonData = JsonConvert.SerializeObject(listMessage);
                }

FieldName = b.FieldName + '|' + b.DataType 我想这样多列合为一列,,但是报错:索引(从零开始)必须大于或等于零，且小于参数列表的大小。这个要咋写????
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using (WcfDataEntities DbContext = new WcfDataEntities())
                {
                    var listFields = from a in DbContext.ObjectList
                                     join b in DbContext.FieldList.AsEnumerable()
                                     on a.AutoID equals b.ParentRowID
                                     where a.ObjectName == strTableName && a.ObjectType == "T"
                                     orderby b.Sort
                                     select new MessageInfo
                                     {
                                         AutoID = b.AutoID,
                                         FieldName = b.FieldName + "
------解决思路----------------------
" + b.DataType,
                                         FieldNameCh = b.FieldNameCh
 
                                     };
                    var listMessage = listFields.ToList<MessageInfo>();
                    strJsonData = JsonConvert.SerializeObject(listMessage);
                }

------解决思路----------------------
string.Format()?
把单引号改成双引号？
------解决思路----------------------
 FieldName = b.FieldName + "
------解决思路----------------------
" + b.DataType,