Did you use SELECT FOR UPDATE at all, or just never had to update dependent data? If the complex operations are implemented using stored functions / procedures then the a transaction is implicit.
If the data is fairly straightforward like just one-to-many CRUD with no circular references, you would be able to do it without transactions, just table relationships would be enough to ensure consistency.
If the data is fairly straightforward like just one-to-many CRUD with no circular references, you would be able to do it without transactions, just table relationships would be enough to ensure consistency.