When I come to amend a table in SQL Server all is fine until you come to save the new structure you end up getting the following message:
"Saving changes is not permitted. The changes you have made require the following tables to be dropped and re-created. You have either made changes to a table that can't be re-created or enabled the option Prevent saving changes that require the table to be re-created."
This is happening because ""Prevent saving changes that require table re-creation" option is enabled. You can disable this by going into Tools -> Options -> Designers-> Uncheck "Prevent saving changes that require table re-creation", this is either in Visual Studio or SQL Management Studio.
Now you can apply your new changes to the table