Change an entity's type

In Scipio, I can change the code in entitymodel.xml and create entities -> create entries within SQL table.
But, what if later on I wish to change the entity’s type from, let’s say, text type to Boolean type so I change the appearance from blank to checkboxes? Will previously entered text data be properly deleted in SQL or will they simply lose connection to the application?

It depends on the field you are going to alter. In general, I’d advice to not change field types, but if you really need to, note that data loss will happen for that field. Besides, some field types changes may have a bad impact in the system as well, unless you also adjust to the proper type in all the places where it is used.