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Database Architecture

Standardization of database systems is a very beneficent in terms of future growth, because once a system is defined to follow a specific standard, or is built on a specific standard, it provides us the ease of use in a number of aspects. First if any organization is going to create a new system of the same usage shall create the system according to the standards and it will be easier to develop, because the standards which are already define will be used for developing the system. Secondly if any organization wants to create and application software that will provide additional support to the system, it will be an easier task for them to develop such system and integrate them into existing database applications. Users which will be using the system will be comfortable with the system because a system built on predefined standards is easy to understand and use, rather than understanding learning and using an altogether new system which is designed and built without following any standards.

Expansion to systems which are not built on standards is very hard and needs lots of efforts. Technical staff working on a system built on standard has no problem to learn the use and architecture of the system and whenever there is a need in change of staff new staff members can be hired and put to work without any prior training for the use of system. Database standard proposed by ANSI SPARK in 1975 is being used worldwide and is the only most popular agreed upon standard for database systems. The Three Level Schema architecture provides us a number of benefits. For accessing data at different levels we have a number of users because not all users have to access data in database at all the database levels. The 3 levels architecture allows us to separate the physical representation of data from the users’ views of data. In the database, same data is stored in a specific feasible format and is available to different users in different formats as desired by different users. For example, consider we have stored the DOB (Date of Birth) in the database in a particular format, like in the form of ddmmyyyy (for example, 28031987). However, the users from different departments may require to view the date of birth in different forms; the examination department may ask it to be displayed as monthdayyyyy (like march281987) the Registrar’s office may ask to display date of birth as mm/dd/yyyy, still the Library may need the in the form of dd/mm/yy. The Three Level Schema allows us to access the data in different formats at the external level, which is stored in a specific format at the internal level. The Three levels architecture is useful for hiding the details of internal systems; it infact hides the details of underlying system views from the users at other levels and restricts the access of data and the system from any unauthorized intervention. It is the mechanism which allows us to store the data in the system in such a way that it can be provided to all users in their desired formats and with unveiling other details and information stored in the database. Moreover if there is a change to be done to the data stored in the database subject to the requirements of a specific user it needs not be changed for that user specifically, we can create a change to the specific external view of that user and the internal details remain unchanged. Also if we want to change the underlying storage mechanism of the data stored on the disk we can do it without affecting the internal and conceptual view at the lowest level in the three levels architecture is the internal view or internal level which is shown below in the diagram and is illustrated in the coming lines.

Fig. 1: Three level architecture of database