How to add inline TVF with dynamic columns from CRL Dynamic Pivot

Question

Hi I am trying to implement the code in the following article.
SQLServerCentral Aricle
Now, I've pushed the assembly to my DB and can see it there. 
So far I have tried building an Inline TVF, as I assume this is how it would be used on the DB; however, I am receiving the following error on my code, I must
be missing a step somewhere, as I've never done this before. I'm lost on how to implement this clr function on my db?
Create Function script:
CREATE FUNCTION clrDynamicPivot
@query nvarchar(4000),
@pivotColumn nvarchar(4000),
@selectCols nvarchar(4000),
@aggCols nvarchar(4000),
@orderBy nvarchar(4000)
RETURNS TABLE
AS
return
(external NAME CLRfunctions.RIFunctions.clrDynamicPivot)
GO
Error:
Msg 156, Level 15, State 1, Procedure clrDynamicPivot, Line 18
Incorrect syntax near the keyword 'external'.
public static void CreateTempTable(SqlString query)
            using (SqlConnection sqlconn = new SqlConnection("Context Connection=True"))
                SqlCommand sqlCmd = sqlconn.CreateCommand();
                sqlCmd.CommandText = query.ToString();
                sqlconn.Open();
                sqlCmd.ExecuteNonQuery();
 public static string GetPivotData(string pivotColumn)
            string stmt = string.Format("select distinct {0} from #temp", pivotColumn);
            string pivotCols = string.Empty;
            using (SqlConnection cn = new SqlConnection("Context Connection=True"))
                SqlCommand cmd = cn.CreateCommand();
                cmd.CommandText = stmt;
                cn.Open();
                using (SqlDataReader dr = cmd.ExecuteReader())
                    while (dr.Read())
                        if (dr.GetFieldType(0) == typeof(System.Int32))
                            pivotCols += "[" + dr.GetInt32(0) + "],";
                        if (dr.GetFieldType(0) == typeof(System.Decimal))
                            pivotCols += "[" + dr.GetDecimal(0) + "],";
                        if (dr.GetFieldType(0) == typeof(System.String))
                            pivotCols += "[" + dr.GetString(0) + "],";
            return pivotCols.Remove(pivotCols.Length - 1);
[Microsoft.SqlServer.Server.SqlProcedure(Name="clrDynamicPivot")]
public static void clrDynamicPivot(SqlString query, SqlString pivotColumn, SqlString selectCols, SqlString aggCols, SqlString orderBy)
    string stmt = string.Empty;
    try
       CreateTempTable(query);
       string pivot = GetPivotData(pivotColumn.ToString());
       stmt = string.Format("select * from ( select {0} from #temp ) as t pivot ( {1} for {2} in ( {3} )) as p {4}",
       selectCols.ToString(),
       aggCols.ToString(),
       pivotColumn.ToString(),
       pivot,
       orderBy.ToString());
       using (SqlConnection cn = new SqlConnection("Context Connection=True"))
          SqlCommand cmd = cn.CreateCommand();
          cmd.CommandText = stmt;
          cn.Open();
          SqlDataReader reader = cmd.ExecuteReader();
          SqlContext.Pipe.Send(reader);
     catch (Exception ex)
       throw new Exception(string.Format("clrDynamicPivot Error stmt:{0}", stmt), ex);
DECLARE @query nvarchar(4000)
DECLARE @pivotColumn nvarchar(4000)
DECLARE @selectCols nvarchar(4000)
DECLARE @aggCols nvarchar(4000)
DECLARE @orderBy nvarchar(4000)
set @query = 'select PayMethod, datepart(hh, OrderDate) as OrderHour, ProductTotal into #temp from dbo.Orders (nolock) where OrderDate between getdate()-1 and getdate() and division = ''15'''
set @pivotColumn = 'PayMethod'
set @selectCols = 'PayMethod, OrderHour, ProductTotal'
set @aggCols = 'sum(ProductTotal)'
set @orderBy = ''
EXECUTE dbo.clrDynamicPivot
@query
,@pivotColumn
,@selectCols
,@aggCols
,@orderBy
GO

Answer 1

You can't build an inline TVF in SQLCLR, only (the equivalent of) multi-statement TVFs and scalar functions. And the SQLCLR code for multi-statement TVFs must be coded with a specific pattern, see
https://msdn.microsoft.com/en-us/library/ms131103.aspx.
Looking at the example you reference, it was implemented as a SQLCLR stored procedure.
Cheers, Bob