Page 176 - DCAP104_EXPOSURE_TO_COMPUTER_DISCPLINES

Unit 8: Database System

one or more database administrators who may control each function, as well as provide other Notes
users with various levels of administration rights. This flexibility makes the task of using DBMS
methods to oversee a system something that can be centrally controlled, or allocated to several
different people.
There are four essential elements that are found with just about every example of DBMS currently
on the market. The first is the implementation of a modeling language that serves to define the
language of each database that is hosted via the DBMS. There are several approaches currently
in use, with hierarchical, network, relational, and object examples. Essentially, the modeling
language ensures the ability of the databases to communicate with the DBMS and thus operate
on the system.
Second, data structures also are administered by the DBMS. Examples of data that are organized
by this function are individual profiles or records, files, fields and their definitions, and objects
such as visual media. Data structures are what allow DBMS to interact with the data without
causing and damage to the integrity of the data itself.

A third component of DBMS software is the data query language. This element is involved in
maintaining the security of the database, by monitoring the use of login data, the assignment of
access rights and privileges, and the definition of the criteria that must be employed to add data
to the system. The data query language works with the data structures to make sure it is harder
to input irrelevant data into any of the databases in use on the system.

Last, a mechanism that allows for transactions is an essential basic for any DBMS. This helps to
allow multiple and concurrent access to the database by multiple users, prevents the manipulation
of one record by two users at the same time, and preventing the creation of duplicate records.

A database management system (DBMS) consists of software that operates databases, providing
storage, access, security, backup and other facilities. Database management systems can be
categorized according to the database model that they support, such as relational or XML, the
type(s) of computer they support, such as a server cluster or a mobile phone, the query language(s)
that access the database, such as SQL or XQuery, performance trade-offs, such as maximum scale
or maximum speed or others. Some DBMS cover more than one entry in these categories, e.g.,
supporting multiple query languages. Examples of some commonly used DBMS are MySQL,
PostgreSQL, Microsoft Access, SQL Server, FileMaker, Oracle, Sybase, dBASE, Clipper, FoxPro
etc. Almost every database software comes with an Open Database Connectivity (ODBC) driver
that allows the database to integrate with other databases.
Figure 8.6: A Generic High Level View of a Database Management System

Database DOMS
system
Application Database User 1
Program 1
Application
Program 2
User 2
Application
Program 3
User 3
Application
Program 4

LOVELY PROFESSIONAL UNIVERSITY 169