Questions

Candidate Key – A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key. 

Primary Key – A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key.

• One needs to be very careful in selecting the Primary Key as an incorrect selection can adversely impact the database architect and future normalization. For a Candidate Key to qualify as a Primary Key, it should be Non-NULL and unique in any domain.

The Aufbau Principle states that in the ground state of an atom, an electron enters the orbital with lowest energy first and subsequent electrons are fed in the order of increasing energies.

Meteorology is the study of weather and Earth's atmosphere. Climatology is another term used to describe the study of weather.

Studying the weather is not only useful for determining if you'll need an umbrella for the day. While forecasting is an important aspect of studying weather, understanding weather patterns provides valuable information about the status of the planet.

Clay is an example of Aquiclude.

Environmental science is a field that integrates physical, biological and information sciences to the study of the environment, and the solution of environmental problems. This emerged from the fields of natural history and medicine during the Enlightenment.

In brief, it is a scientific study of the natural world and how it is influenced by people.