Effect Of Calling Real Service Call In Test?

I am trying to understand the effect of calling real business logic from the test class. If I have a test class that call the service method which make update to DB. Is DB really changes through test class?

e.g.

Java Code: @Test
public void testUpdate() {
MyDto myDto = new MyDto(paramters to create new myDto object); //creating new dto object
myService.updateMyData(myDto); //passing new dto object for update (DB record really changed??)
MyDto testDto = myRepo.find(myDto.getKey()); //get record for the corresponding key
assert testDto.getSomeProp() == myDto.getSomeProp(); //what testDto.getSomeProp() return? new value send on myDto or old value from DB?
} mh_sh_highlight_all('java');