Hibernate, triggers and yo-yo update

While using Hibernate to manage DB operations in your application you may also need to use triggers to perform specific updates directly inside DB. But if you're using both update methods it's essential to protect yourself against yo-yo effect.

Concatenating with NULLs in SQL

A concatenation of 2 or more values in SQL looks like a pretty simple operation. It's enough to use '||' operator which comes in SQL standard. Well, it turns out that this is not so trivial in case of NULL values.