WHY A DATABASE - IBM Mainframe

Why should an organization have an integrated database to store its operational data? A general answer to this question is that a database system provides the organization with centralized control of its data. The situation that prevails in many enterprises is that each application has its own private files in its own tapes and disks, so the data is widely dispersed and therefore difficult to control. Deficiencies of pre-database information processing include (but not limited to) the following:

  • Encoded data (data hard-coded in the application)
  • Interdependence between programs and data files
  • Data repetition or redundancy
  • Data inconsistency
  • Lack of data integrity
  • Ad hoc representation of relationships
  • Ad hoc data management techniques
  • Lack of coordination across applications using common data
  • Lack of foolproof data security mechanisms
  • Inability to manage concurrent access to data
  • Non-uniform back-up and recovery methods

The advantages of having the data in a database are summarized below:

  • Redundancy can be reduced - In non-database systems, each application or department has its own private files resulting in considerable amount of redundancy of the stored data. Thus storage space is wasted. By having a centralized database most of this can be avoided. We do not say or suggest that all redundancy should be eliminated. Sometimes there are sound business and technical reasons for maintaining multiple copies of the same data. In a database system, however, this redundancy can be controlled.
  • Inconsistency can be avoided - This is really a corollary to the above point. When the same data is duplicated and changes are made at one site, which is not propagated to the other site, it gives rise to inconsistency. Then the two entries regarding the same data will not agree. At such times the data is said to be inconsistent. So if the redundancy is removed chances of having inconsistent data is also removed.
  • Data can be shared - The existing applications can share the data in a database.
  • Standards can be enforced - With the central control of the database, the database administrator can enforce standards.
  • Security restrictions can be applied - Having complete authority over the operational data enables the database administrator (DBA) in ensuring that the only means of access to the database is through proper channels. The DBA can define authorization checks to be carried out whenever access to sensitive data is attempted. Different checks can be established for each type of access (retrieve, modify, delete, etc.) to every piece of information in the database.
  • Integrity can be maintained - Integrity means that the data in the database is accurate. Centralized control of the data helps in permitting the administrator to define integrity constraints to the data in the database.
  • Conflicting requirements can be balanced - Knowing the overall requirements helps the database designers in creating a database design that is best for the organization.

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