Indexes can be unique or nonunique. Unique indexes guarantee that no two rows of a table have duplicate values in the key column or columns. For example, no two employees can have the same employee ID. Thus, in a unique index, one rowid exists for each data value. The data in the leaf blocks is sorted only by key.
Energy exists in many different forms. Examples of these are: light energy, heat energy, mechanical energy, gravitational energy, electrical energy, sound energy, chemical energy, nuclear or atomic energy and so on. These forms of energy can be transferred and transformed between one another.
Types of Energy. There are two types of energy: Potential (or stored energy) Kinetic (or energy in motion) Kinetic Energy is energy in motion. Moving water and wind are examples of kinetic energy. Electricity is kinetic energy because, even though you can't see it happen, electricity involves electrons moving in a conductor. Potential Energy is stored (or latent). Energy can be stored in many ways. A gallon of gasoline or a barrel of oil contains stored energy that can be released when we burn it.