If you are nice and work hard, they won't give you an NOC because they won't want another company to have a nice, hardworking staff member like you.
If you are tough and rude, they won't give you an NOC because they won't like you.

Seriously - to answer your first question: "Can I have the right to ask for a NOC" the answer is a big, fat NO. You have NO right to ask, demand, expect or hope for an NOC. You DO NOT have a right in Qatar to change jobs without your sponsor's permission.