What is the application of temporal database? Describe different types of time occur in temporal database.

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 There are many applications of the temporal database are f(reservation systems, scientific databases, company databases, university databases,s, etc.) where some aspect of time is needed to maintain the information in a database

  •  Insurance, where claims and accident histories are required as well as information about the times when insurance policies are in effect;
  •  Reservation systems in general (hotel, airline, car rental, train, and so on), where information on the dates and times when reservations are in effect is required;
  •  Scientific databases, where data collected from experiments include the time when each data is measured; and so on
  • In the COMPANY database, we may wish to keep SALARY, JOB, and PROJECT histories on each employee
  •  In the UNIVERSITY database, time is already included in the SEMESTER and YEAR of each SECTION of a COURSE, the grade history of a STUDENT, and the information on research grants. 
  • In fact, it is realistic to conclude that the majority of database applications have some temporal information. 
  • However, users often attempt to simplify or ignore temporal aspects because of the complexity that they add to their applications.

2nd part

The different times that occur on the temporal database are : Valid time, Transaction time, bitemporal data

Valid time

Valid time is a time period during which a fact is true in the real world. Given a particular event or fact that is associated with a particular time point or time period in the database, the association may be interpreted to mean different things. The most natural interpretation is that the associated time is the time that the event occurred or the period during which the fact was considered to be true in the real world. If this interpretation is used, the associated time is often referred to as the valid time. A temporal database using this interpretation is called a valid time database.
For example, in a company, the Salary of the employees has a valid time and end time

Transaction time

Transaction time is the time period during which a fact stored in the database was known.
However, a different interpretation can be used, where the associated time refers to the time when the information was actually stored in the database; that is, it is the value of the system time clock when the information is valid in the system. In this case, the associated time is called the transaction time. A temporal database using this interpretation is called a transaction time database. Unlike valid time here we can roll back the database. For example, in a company, the Salary of the employees has a valid time and end time. 


Bitemporal data

It combines both valid ad transaction times. It stores data with respect to both valid time and transaction time. In some applications, only one of the dimensions is needed and in other cases, both time dimensions are required, in which case the temporal database is called a bitemporal database.


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