Is moving to another city to study at university much different to staying in one's home town?

Yes, its quite different. Similar to being stranded in the middle of nowhere and figuring out how to get out of that situation.

Well, not that extreme but you are completely on your own, in a new place, with no friends or family. You are exposed to a new culture, different way of learning etc.

Sounds scary but highly recommended. Chose a place that is in a different continent and completely different from what you have been exposed to. In the long run the experience will really broaden your horizons and make you a global citizen.
Are Oracle Database certifications worth it?

Are Oracle Database certifications, worth it?All certifications have some values attached to them They are a measuring gauge specially for employers to judge the worth of the candidate. Similarly a certification is proof that an individual has gained knowledge in a particular field.

If I stop counting calories, will I gain weight?

It is very hard to tell what will happen with you, but it is worth considering that most slim people don't count calories. What they (we) do tend to do is maintain a reasonably honest view of how their eating