public static SqlInt32 clr_MyFunc()
    {
        using (SqlConnection conn = new SqlConnection("Context Connection = true"))
        {
            conn.Open();
            SqlCommand cmd = new SqlCommand("SELECT parameter FROM my_table WHERE iid = 4", conn);
            return (SqlInt32)cmd.ExecuteScalar();

        }
        
    }

public partial class StoredProcedures
{
    [Microsoft.SqlServer.Server.SqlProcedure]
    public static void sp_MyProc(int FunctionID, int Identifier)
    {
        using (SqlConnection conn = new SqlConnection("context connection = true"))
        {
            conn.Open();
            string s = "";
            // Выбираем одну из table-valued функций с одинаковым входным параметром @IID int
            switch (FunctionID)
            {
                case 1:
                    s = "dbo.Func1";
                    break;

                case 2:
                    s = "dbo.Func2";
                    break;

                case 3:
                    s = "dbo.Func3";
                    break;

                default:
                    s = "dbo.Func4";
                    break;
            }

            SqlCommand cmd = new SqlCommand(s, conn);
            cmd.CommandType = CommandType.Text;
            cmd.CommandText = String.Format("SELECT IID FROM {0}(@IID)", s);

            SqlParameter param = new SqlParameter("@IID", SqlDbType.Int, 4, ParameterDirection.Input, 10, 0, null, DataRowVersion.Current, false, Identifier, "", "", "");
            cmd.Parameters.Add(param);
            SqlDataReader rdr = cmd.ExecuteReader();

            // Пересылаем данные клиенту
            SqlContext.Pipe.Send(rdr);

            conn.Close();
        }
    }
};

Configuration option 'clr enabled' changed from 1 to 1. Run the RECONFIGURE statement to install.