Write to database

The update mechanism corresponds a little bit to the situation as being in a program. After selecting an instance in a property handle, one may change one or more values using value access functions. Any change raises a modified flag for the instance, but data is not yet stored to the database.

The application may read the updated values and will get the modified data, but other applications do not so, as well as other property handles (property handles with a different cursor).

When changing the selection in a property handle, which contains a modified instance, data is stored automatically. This may lead to conflicts, e.g. because of duplicate key values after changing key attributes. Hence, it is sometimes more safe to store the instance explicitly by calling save().

save() will also store updates instances for subordinated property handles, i.e. it is sufficient calling save() for the topmost updated property handle.

Especially when running updates in a transaction, the application should store all updates before committing the transaction. Otherwise changes become not part of the transaction.