The solution for errormessage:
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 thar can’t be re-created or enabled the option Prevent saving changes that require the table to be re-created.
Go to Tools –> Options –> Designers –> Table and database designers
Uncheck the checkbox: “Prevent saving changes that require the table to be re-created”
But won’t that make the table be dropped and re-created, and thereby losing all data?
Another solution is just to open a new query window and just write the appropriate alter table command. That has worked every time I have seen this message.
The strange thing is – you get this message even if the table won’t get dropped and recreated, I get it when I for example change a column to auto increment.
If you try to make a change that affects data you get the message: “- Warning: Data might be lost converting column”
Good point about alter table – however, you could potentially loose data that way too?