DBMS(Database Management System)

  Database Management System 

A. Functions of DBMS

>Data Definition

-The DBMS must be able to accept data definitions (Externals, internal and conceptual schemas, and all associated mappings) in source form and convert to the appropriate object form.

>Data Manipulation

-The DBMS must be able to handle request from the user to retrieve and possibly existing data in the database, or to add a new data to the database.

>Data Security and Integrity 

-The DBMS must be able to monitor user requests and reject any attempts to violate the security and integrity checks defined by the database administrator.

>Data Recovery and Concurrency

-The DBMS must have the capability of recover from, ok r minimize the effects of a system crash.

>Dara Dictionary

-The DBMS must provide a system database called the database dictionary. 

B. Advantage of DBMS

>Reduced Data Redundancy

-In database system, system redundancy us avoided by keeping a single copy of the data.

>Data Integrity

-Since a single copy of a particular data is stored in the database you can be certain that the changes to the data will be reflected in all future uses of the data.

>Data Independence

-The structure of the database system requires that data be independent of their data u the database and the software used to access the database.

>Data Security

-A database system can have additional security measures as part of the database software product.

>Data Consistency

-Data Consistency is maintained in the database environment.

>Easier use of Data

-Data is easier to use un the database environment.

>Less storage

-Since data redundancy us reduce if not eliminated, the database will occupy less storage space.

C. Disadvantage of DBMS

>Complexity

-Databse nd their associated DBNS are extremely complex.

>Expense

-The installation of the DBMS and it's databws onto the current system requires careful planning because of the possibility of the need for additional hardware.

>Vulnerability

-Because data in a database is an a central location, it is vulnerable to partial or complete destruction when a breakdown of hardware components occur or in software mistake.

>Size

-A typical maintenance database is very large.

>Training costs

>When a company purchase a database products it must first train one or more individuals to be the database administrator for the new product.

>Compatibility

-One of the pitfalls of most database systems us their incompatibility with other database system.

>Looking-In of Technology

-What if the vendor expresses desire to abandon the product? There is a possibility that they will have to redesign their system from scratch.