Unable to SaveChanges() after adding new fields to model&vie

I have just downloaded one of your project on webtimemanagement.

I have successfully run and all worked but when I tried to add new input via model and also in the view class I get error

{0}Int32 SaveChanges()

Inner Exception is {0}System.Data.Entity.Core.UpdateException: An error occurred while updating the entries. See the inner exception for details. ---> System.Data.SqlClient.SqlException: Invalid column name 'ItemDesc'.

Invalid column name 'Quantity'.

Invalid column name 'Price'.

Invalid column name 'Amount'.

The three field truly are not in the database. Is there a way I can exclude them from saving because I only need to concatenate them and add them to a field that is in the database called Purpose/Reason.

Please help me, I am new to ASP.Net MVC