Import data from Excel to sqlserver with additional field

-> In excel file

ID	Name	Location1
1	Jubayer	Dhaka
2	Jakia	Dhaka
3	Khalid	Dhaka
4	Jamal	Manikgonj
5	Alim	West

 ->create a database and table in sql server

 ->c# code

<div>

   

        <asp:FileUpload ID="FileUpload1" runat="server" />

        <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />

        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

   

    </div>

if (FileUpload1.HasFile)   //Upload file here

            {

                FileUpload1.SaveAs(@"C:/temp/" + FileUpload1.FileName);

                string pat = @"C:/temp/" + FileUpload1.FileName;

                string path2 = string.Concat(Server.MapPath("App_Data/upload/" + FileUpload1.FileName));

                string excelConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source='" + pat + "';Extended Properties=" + '"' + "Excel 8.0;HDR=YES;" + '"';

                string file_out_ex = Path.GetFileNameWithoutExtension(path2);

               

                string CONSTANTVALUE = "Test";

//                string excelsql = "SELECT * FROM [Details$]";

                string excelsql = "select ID, Location1, '" + CONSTANTVALUE + "' as EXCELCUSTOM from [Details$]";

              

                using (OleDbConnection connection = new OleDbConnection(excelConnectionString))

                {

                    OleDbCommand command = new OleDbCommand(excelsql, connection);

                    connection.Open();

                    using (DbDataReader dr = command.ExecuteReader())

                    {

                        string sqlConnectionString = ConfigurationManager.ConnectionStrings["db_connection_string"].ConnectionString;

                        using (SqlBulkCopy bulkCopy = new SqlBulkCopy(sqlConnectionString))

                        {

                            bulkCopy.DestinationTableName = "Cities";

                            SqlBulkCopyColumnMapping mapping1 = new SqlBulkCopyColumnMapping("ID", "long");

                            SqlBulkCopyColumnMapping mapping2 = new SqlBulkCopyColumnMapping("Location1", "city");

                            SqlBulkCopyColumnMapping mapping3 = new SqlBulkCopyColumnMapping("EXCELCUSTOM", "lati");

                          //  bulkCopy.ColumnMappings.Add("TABLECOLUMN3", "ConstantCol");

                           // "TABLECOLUMN1", "EXCELCOLUMN1"

                            bulkCopy.ColumnMappings.Add(mapping1);

                            bulkCopy.ColumnMappings.Add(mapping2);

                            bulkCopy.ColumnMappings.Add(mapping3);

                            try

                            {

                                bulkCopy.WriteToServer(dr);

                            }

                            catch (Exception ex)

                            {

                                Label1.Text = "The following problems occurs: " + ex.Message;

                            }

                            finally

                            {

                                dr.Close();

                            }

                        }

                    }

                }

            }

        }catch(Exception ex){

            throw ex;

        }