【单选题】Which of the following conditions will make a relation that is in first normal form. to be in second normal form? Ⅰ.every non-key attribute is functionally dependent on the full set of primary key att...
【单选题】Eco-travel is a form of travel _____ combines normal tourism with learning, _____ a way to find out what can be done to help animals, plants and people. [ ]