Join two dynamic Linq in Asp.net - asp.net

Question

I have used linq to store data, below is the code:
var result = (dynamic)null;
var serviceData = (dynamic)null;
var userData = (dynamic)null;
/****Linq 1*****/
serviceData= dtPasscode.AsEnumerable().Select(m => new
{
ACCOUNT_ID = intAccountId,
SUB_ACC_ID = m.Field<string>("ACCOUNT_ID_ALIAS")
});
/**Linq 2**/
userData = DisplyCustomerDetails(Convert.ToInt64(strSubAccountID));
result = serviceData.Concat(userData);
And another linq through function:
/**Function**/
System.Data.EnumerableRowCollection DisplyCustomerDetails(Int64 intAccountId)
{
var result = (dynamic)null;
/** Data Display if no service avaiable **/
IAccount_BL objAccount_BL = new Account_BL();
Customer objCustomer = new Customer();
DataTable dtCustomer = null;
int intErrorCount = 0;
objCustomer.Account_Id = Convert.ToInt64(intAccountId);
dtCustomer = objAccount_BL.GetCustomerDetails(objCustomer, ref intErrorCount);
objAccount_BL = null;
objCustomer = null;
if (intErrorCount == 0)
{
if (dtCustomer != null)
{
if (dtCustomer.Rows.Count > 0)
{
result = dtCustomer.AsEnumerable().Select(m => new
{
ACCOUNT_ID = intAccountId,
SUB_ACC_ID = m.Field<string>("ACCOUNT_ID_ALIAS")
});
}
}
}
return result;
}
I wanted to join both the result of Linq1 & Linq2, I tired Concat & Union, getting below error
'System.Data.EnumerableRowCollection<<>f__AnonymousTypea>' does not contain a definition for 'Concat'

Answer 1

To Concat both enumerables must of the same class; you cannot use anonymous classes. Define a class that has the two fields and change the code to Select them.
Also, don't use ... = (dynamic) null; just assign the variable directly
var serviceData= dtPasscode ...
var userData = DisplyCustomerDetails ...
var result = serviceData.Concat(userData);