I'm currently developing a Spring-based web-application, in which almost every operation create/update/delete something in the database. The logic mostly about checking condition so as to we should create/update records in the database or not.
The reason I want to try unit test is that we often meets regression errors when request changes or refactor. Most the bugs comes from Database changes, when I doesn't fully reflect those changes in the code. I have some experience in web-development now, but it seems that's not enough to stop them appear.
I'm investigating unit test, and I heard that when it comes to database operation, it's no longer unit test, since the test will be slow. Is that true? So that if my project is heavily database-operation, I shouldn't use unit test?
I also heard about DBUnit & some in-memory database which can quicken the test. Should I use them? And how I can write good unit test for database operation?