Database Management
Organizations use large amounts of data. These data can be related to the people who
work for the organization, its products or services, the customers or any other aspect of the
operations of the organization. The data need to be organized in a way that supports decisionmaking. The most common data types are text and numbers, but data can also include images,
photographs, sound, video and other types. Data are organized in a database.
This is an example of how databases are used:
Think of a public library. A library contains books, magazines, CDs, DVDs and other
materials. All these materials need to be catalogued so we know what is available in the
library. For each item, the catalog would describe things like the type of item, the title, the
authors, the publishers and other relevant details. The catalog also needs to be searchable, so
the librarian typically assigns some keywords to each item. The library catalog is a type of
database.
Once we have a catalog, we also need to have a way for users to check out the materials.
Users need to be able to register, get a library card and use this card to check out the materials
they want to take home. So the library needs a database of users. This would include the
user's name, address, telephone number, e-mail and age. With a catalog of materials and a
user database, the library can start operating. What is needed to support the day-to-day
operations is a system to keep track of which materials each user checks out and when they
get returned. This system needs to be linked to the catalog and the user database.
Now consider how you actually use the library and what decisions are being made. You
go to the library and want to learn something about the theory of evolution. The first thing
you probably do is go to a computer terminal and search the catalog with a keyword like
'evolution theory.' You browse through the results to see which books might be most useful.
Once you have found a few titles, you can check to make sure they are not already checked
out.
You find the materials you are interested in on the shelves and take them to the checkout
counter. The staff at the counter scans your library card to make sure your account is in good
standing. If you have books overdue, the staff member will be quick to remind you. Then the
materials you want to check out are scanned, and the staff member will make sure you don't
exceed any limits set by the library - such as a maximum of three music CDs.
You take your materials home, and a week later you get a reminder e-mail that your
music CDs are due, since you can only keep them for a week. You return the music CDs but
keep the books for now. Two weeks later, you get a reminder your books are due. You are
not quite done reading them, so you log on to the library's website and renew the books
online. A few weeks later, you return the books.
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Throughout these steps, you have used the library system in several ways:
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The catalog terminals at the library
The checkout counters
The e-mail notification system, and
The online renewal system
All of this is possible because of the database systems maintained by the library.
Also consider how the library staff uses the databases. Staff at the checkout counters
process user requests. Librarians add new books to the catalogue and help users find
materials at other libraries. Senior staff at the library analyze how the collections are being
used, which new materials should be acquired and how to best meet the needs of the many
library users. All of these decisions are informed by the various databases.1
Database management is a system to define, manipulate, retrieve and manage data in a
Database. Generally, a database management manipulates the data itself, the data format,
field names, record structure and file structure. It also defines rules to validate and manipulate
this data. A Database management system relieves users of framing programs for data
maintenance. Techopedia, explain too that a database is the back-end of an application. A
database management system receives instruction from a database administrator and
accordingly instructs the system to make the necessary changes. These commands can be to
load, retrieve or modify existing data from the system.
A database management system always provides data independence. Any change in
storage mechanism and formats are performed without modifying the entire application.
There are four main types of database organization:
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Relational Database: Data is organized as logically independent tables. Relationships
among tables are shown through shared data. The data in one table may reference
similar data in other tables, which maintains the integrity of the links among them.
This feature is referred to as referential integrity - an important concept in a relational
database system. Operations such as "select" and "join" can be performed on these
tables. This is the most widely used system of database organization.
Flat Database: Data is organized in a single kind of record with a fixed number of
fields. This database type encounters more errors due to the repetitive nature of data.
Object Oriented Database: Data is organized with similarity to object oriented
programming concepts. An object consists of data and methods, while classes group
objects having similar data and methods.
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Hierarchical Database: Data is organized with hierarchical relationships. It becomes
a complex network if the one-to-many relationship is violated2
To organize amounts of data, a database management system (DBMS) will help. It is a
software tool that makes it possible to organize data in a database. The standard acronym for
database management system is DBMS, so you will often see this instead of the full name.
The ultimate purpose of a database management system is to store and transform data into
information to support making decisions.
A DBMS consists of the following three elements:
 The physical database: the collection of files that contain the data
 The database engine: the software that makes it possible to access and modify the
contents of the database
 The database scheme: the specification of the logical structure of the data stored
in the database
While it sounds logical to have a DBMS in place, it is worth thinking for a moment about
the alternative. What would the data in an organization look like without a DBMS? Consider
yourself as the organization for a moment, and the data are all the files on your computer.
How is your data organized? If you are like most typical computer users, you have a large
number of files, organized in folders.
You may have word processor documents, presentation files, spreadsheets, photographs,
etc. You find the information you need based on the folder structure you have created and the
names you have given to your files. This is called a file system and is typical for individual
computer users.
Now consider the challenges you are faced with. Have you ever lost a file? Have you had
difficulty finding a file? Probably. Perhaps you are using multiple computers and your files
are located in different physical locations. And when was the list time you created a backup
of all your files? You do back up, right?
You probably get the picture. A file system is relatively simple, but it only works if you
keep yourself very organized and disciplined. Now consider an organization with 1,000
employees, each with their own computer. Can you see some of the challenges when using a
file system? Do you really want critical financial data floating around the offices as simple
files on individual computers?
So what does a DBMS really do? It organizes your files to give you more control over
your data. A DBMS makes it possible for users to create, edit and update data in database
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files. Once created, the DBMS makes it possible to store and retrieve data from those
database files.
More specifically, a DBMS provides the following functions:
 Concurrency: concurrent access (meaning 'at the same time') to the same database
by multiple users
 Security: security rules to determine access rights of users
 Backup and recovery: processes to back-up the data regularly and recover data if
a problem occurs
 Integrity: database structure and rules improve the integrity of the data
 Data descriptions: a data dictionary provides a description of the data
Within an organization, the development of the database is typically controlled
by database administrators (DBAs) and other specialists. This ensures the database structure
is efficient and reliable.
Database administrators also control access and security aspects. For example, different
people within an organization use databases in different ways. Some employees may simply
want to view the data and perform basic analysis. Other employees are actively involved in
adding data to the database or updating existing data. This means that the database
administrator needs to set the user permissions. You don't want someone who only needs to
view the database to accidentally delete parts of the database.3
Ratu Fauziah,
Februari, 12th 2015
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