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What is a Database Application? How is Testing done at the Database layer?

Database applications are more famous than any other kind of software systems or applications. “A data base application is just like any other computer but with the purpose of retrieving and entering the information from and in to a data base managed by a computer system”.
Accounting systems and railway and airline reservation system present some good examples of the data base. Earliest of the data base applications were developed in the year of 1957. Modern data bases are known by their characteristic of facilitating the simultaneous queries and updates from multiple users. The purpose that is served by data bases was accomplished by the earlier systems of the year of 1970 by having each user in front of the mainframe computer via a 3270 terminal. The year of 1980 saw some advancement and a personal computer was given to each of the user which had a software system or application running on it which connected the personal computer to the server of the data base.

This software system or application could perform the following tasks:
1. Pull out information from the data base
2. Transmit information over
3. Arrange that information
4. Represent the information in form of a graph
5. Format the information
The coming years saw more sophistication and the data applications with a web interface came in to the scenario. The user would use the same web browser program while using any application rather than developing a custom software to be run on the user’s personal computer.

Advantages of Database Application

A data base application with a web interface had the following advantages.
1. It could be used with devices of many different sizes.
2. It could be used with different hardware.
3. It could be used with different operating systems.

– An example of such a data base application was amazon.com which made use of the oracle relational data base management system.
– The most complex data base applications are those of the accounting systems such as SAP consisting of 1000s of tables in just one single module.
– Facebook is another example built on the top of MySQL.
– It is not necessary that every program using a data base is to be considered a data base application.
– These programs analyze the data and are developed to answer hypothesis rather than putting the information back to the data base.
– Therefore, they cannot be called a data base application. Since data base holds all the critical information it needs to be tested.

To say, data base testing is a layered process actually. 4 layers together constitute the data base namely:
a) The user interface layer
b) The business layer
c) The data access layer and
d) The data base itself

Testing all these 4 layers is important so as to maintain the consistency of the data base. Various types
of testing methodologies are used for testing the data base such as:

1. Black box testing: It involves testing data base integration and interface.
2. White box testing: It involves testing the internal structure of the data base while hiding
the specification details from the user.

Data base testing is carried out in 4 stages:
a) Set fixture
b) Test run
c) Outcome verification
d) Tear down
– The initial state of the data base is described by the test fixture before the data base is set up for the testing. – Once the fixtures have been set, the behavior of the data base is tested for the defined test cases.
– The test cases are decided to be modified or kept as they are based up on the outcome.
– Continuing with the other test cases or terminating the testing process results in tear down.
– The work flow stated below is executed by each of the tests for making the database testing successful:
a) Cleaning up the data base.
b) Setting up the fixture.
c) Running the tests.
d) Verifying the outcomes.
e) Tear down.

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