ASSINGNMENT
CHAPTER 10
Chapter
Review Pages 542 – 543
Discovering
Computer (“Living In the Digital World 2011”)
Lecture :
Student
: Williem
[1701309721]
1.
What Is a
Database, and How Does a database interact with Data and Information?
A database is a collection of
information organized in such a way that a computer program can
quickly select desired pieces of data. You can think of a
database as an electronic filing system or data base is a collection of data organized in a
manner that allows access, retrieval, and use of that data.
To access information from a database, you need
a database management system
(DBMS). This is a collection of programs that enables you to enter,
organize, and select data in a database. Database management system (DBMS) is a software system designed to allow the
definition, creation, querying, update, and administration of databases.
Database software, often called a database management system (DBMS), allows
users to create a computerized database; add, modify, and delete the data; sort
and retrieve the data; and create forms and reports from the data. Data is a
collection of unprocessed items, which can include text, numbers, images,
audio, and video. Computers process data into information. Information is
processed data; that is, it is organized, meaningful, and useful. In addition
to documents, information can be in the form of audio, images, and video.
2.
What Is Data
Integrity, and What Are the Qualities of Valuable Information?
Data integrity refers to
maintaining and assuring the accuracy and consistency of data over its entire life-cycle, and is a
critical aspect to the design, implementation and usage of any system which
stores, processes or retrieves data. Data integrity
identifies the quality of data. Data integrity is important because computers
and people use information to make decisions and take actions. For a computer
to produce correct information, the data that is entered in a database must have
integrity.
For information
to be valuable, it should be:
·
Accurate
information
Accurate information is error free.
Inaccurate information can lead to incorrect decisions.
·
Verifiable
information
Verifiable information can be proven as
correct or incorrect.
·
Timely
Timely information has
an age suited to its use.
·
Organize
Organized information is arranged to
suit the needs and requirements of the decision maker.
·
Accessible
Accessible information is available when the
decision maker needs it.
·
Useful
Useful information has meaning to the
person who receives it.
·
Cost-effective
Cost-effective information should
give more value than it costs to produce.
3. What Is Meant by Character, Field, Record, and File?
·
Character
A bit is the smallest
unit of data the computer can process. Eight bits grouped together in a unit
comprise a byte. In the ASCII coding scheme, each byte represents a single
character, which can be a number (4), letter (R), space, punctuation mark (?),
or other symbol (&). The Unicode coding scheme, by contrast, uses one or
two bytes to represent a character
·
Field is combination
of one or more characters, field is the basic data entry in a record. A field
is a combination of one or more related characters or bytes and is the smallest
unit of data a user accesses
·
Record is a row of
data added to this table. A record is a group of related fields.
·
A data file is a collection
of related records stored on a storage medium such as hard disk or optical
disc.
4.
What Are File Maintenance
Techniques and Validation Techniques?
·
File Maintenance
Refers to the
procedures that keep data current. File maintenance procedures include adding
records to correct inaccurate data or to update old data with new data, and
deleting records when they no longer are needed
·
Validation
Validation is
the process of comparing data with a set of rules or values to find out if the
data is correct. Many programs perform a validity check that analyzes
data, either as you enter it or after you enter it, to help ensure that it is
correct. Types of validity checks include an alphabetic check, a numeric check,
a range check, a consistency check, a completeness check, and a check digit.
5.
How
Is a File Processing Approach Different from the Database Approach?
·
In
simple term, a file processing system coordinates only physical access to data.
A database organizes and coordinate both physical and logical data access.
·
In file processing data redundancy—same fields
stored in multiple file but in Database Approach Reduced data redundancy.
·
In isolated data—data stored in separate files so it
is difficult to access but in Database Approach not difficult to access.
·
A
database specifically reduces the amount of duplication of data in a
system. Additionally, since a database is designed to allow access queries
where a file system only allows pre-determined data access, database queries can be far more
refined and flexible, as well as granting user access privileges data.
·
Databases,
unlike file processing systems, allow multiple protect stored users to access
the same data simultaneously. File processing systems are far more restricted
on this level.
·
The
database's far easier to enforce uniform standards over the data because data can be formatted to fit a particular
screen, allowing a single type of data file to be created across the system for
example.
·
Database
applications are quicker and easier
to develop due to standardized components.
·
Due
to design, databases are far more flexible as well. They can be adapted far
more easily to cope with changing situations than a file
processing system.
·
The
economy of implementing a database across a huge
network is greater than implementing a full file processing system.
·
Databases
are essentially easy to install, and are far more user friendly.
·
In
a file processing system, each department or area within an organization has
its own set of data files. The records in one file may not relate to the
records in any other file. Two major weak- nesses of fi le processing systems
are redundant data (duplicated data) and isolated data.
·
With
a database approach, many programs and users share the data in a database. The
database approach reduces data redundancy, improves data integrity, shares
data, permits easier access, and reduces development time. A database, however,
can be more complex than a file processing system, requiring special training
and more computer memory, storage, and processing power than file processing
systems.
·
Data
in a database also can be more vulnerable than data in file processing systems.
6.
What Functions
Are Common to Most Database Management Systems?
a. The ability to update and retrieve data
This
is a fundamental component of a DBMS and essential to database management.
Without the ability to view or manipulate data, there would be no point to
using a database system.
Updating
data in a database includes adding new records, deleting existing records and
changing information within a record. The user does not need to be aware of how
DBMS structures this data, all the user needs to be aware of is the
availability of updating and/or pulling up information, the DBMS handles the
processes and the structure of the data on a disk.
b. Support Concurrent Updates
Concurrent
updates occur when multiple users make updates to the database simultaneously.
Supporting concurrent updates is also crucial to database management as this
component ensures that updates are made correctly and the end result is
accurate. Without DBMS intervention, important data could be lost and/or
inaccurate data stored.
DBMS
uses features to support concurrent updates such as batch processing, locking,
two-phase locking, and time stamping to help make certain that updates are done
accurately. Again, the user is not aware all this is happening as it is the
database management system’s responsibility to make sure all updates are stored
properly.
c. Recovery of Data
In
the event a catastrophe occurs, DBMS must provide ways to recover a database so
that data is not permanently lost. There are times computers may crash, a fire
or other natural disaster may occur, or a user may enter incorrect information
invalidating or making records inconsistent.
If
the database is destroyed or damaged in any way, the DBMS must be able to
recover the correct state of the database, and this process is called Recovery.
The easiest way to do this is to make regular backups of information. This can
be done at a set structured time so in the event a disaster occurs, the
database can be restored to the state that it was last at prior to backup.
Backup and recovery is brought to mind whenever there is potential outside
threats to a database. For example if there is a power outage, recovery
management is how long it takes to recover the database after the outage.
Backup management refers to the data safety and integrity; for example backing
up all your mp3 files on a disk.
A
disadvantage to this is any data or changes entered after the backup would be
lost. A way to counteract this is to set the DBMS to provide a feature called
Journaling. This involves keeping a log of all updates made to the database, it
is maintained in a file separate from the database and can be obtained to
re-update the database after it is recovered from the backup.
d. Security
Security
is the prevention of unauthorized users accessing the database. DBMS uses
features such as encryption, authentication, authorization and views to provide
security to the database. Encryption is when DBMS converts the data in a
database to an indecipherable format. No unauthorized person trying to access
this information will be able to read it. Authorized users will be able to see
it in normal form.
Authentication
is a technique in which the database administrator can identify the person
accessing the database. Authorized users are given passwords and successful
entry of a valid password will allow the user entry into the database, if a
password is not successfully entered, the user will be denied access.
Authorization is a set of rules that the database administrator (DBA) sets up
to specify levels of usage that individuals or groups are allowed to have. Some
users may only be allowed viewing options, while others may be allowed to both
view/make changes.
In
some circumstances, users may only be allowed to access certain pieces of the
database, and be denied access to areas that does not relate to their specific
needs. In these cases, the DBA will assign workgroups, and these workgroups
will be assigned levels of access and permissions. Views are when DBA allows
certain users the ability to view the tables or fields that pertain to them,
any other view does not exist for them in the database, DBMS does this behind
the scenes and to the user it appears that the information they see are the
only existing data.
e. Data Integrity
Data
integrity is an important function in database management. This is a set of
rules that DBMS provides to see that data integrity is enforced, thus avoiding
incorrect or inconsistent data. Types of integrity that DBMS provides are data
type, legal values and format. Key integrity also falls into this function of
DBMS. This enforces that the primary key of a record remains unique.
7. What Are Characteristics of Relational,
Object-Oriented, and Multidimensional Databases?
A.
Relational Data
Base
a.
Stores data in tables that consist of rows and
columns
b.
Each
row has primary key
c.
Each
column has unique name
d.
Stores data relationships
e.
Uses specialized terminology
to
a file as a table, a record as a row, and a field as a column. A relationship
is a link within the data in a relational database. Structured Query Language
(SQL) allows users to manage, update, and retrieve data in a relational
database.
B.
An Object-Oriented
Database (OODB)
a.
Stores
data in objects. An object is an item that contains data, as well as the
actions that read or process the data.
b.
Advantages
c.
Can
store more types of data
d.
Can
access data faster
e.
Often uses object query language (OQL)
f.
Object-oriented
databases often use an object query language (OQL) to manipulate and retrieve
data.
g.
Applications
appropriate for an object-oriented database include a multimedia database, a
groupware database, a computer-aided design (CAD) database, a hypertext
database, and a hypermedia database.
C.
A Multidimensional
Database
a.
Stores
data in dimensions.
b.
These
multiple dimensions, sometimes known as a hypercube, allow users to access and
analyze any view of the database data.
c.
No
standard query language exists for multidimensional databases.
d.
One
application that uses multidimensional databases is a data warehouse, which is
a huge database that stores and manages the data required to analyze historical
and current transactions.
e.
A
smaller version of a data warehouse is the data mart, which contains a database
that helps a specific group or department make decisions.
f.
Multiple dimensions, also called hypercube, allow
users to analyze any view of data
g.
Can consolidate data much faster than relational
database
8.
How Are Web
Databases Accessed?
Database you access through the Web by filling in a form on a Web page usually
resides on a database server, a computer that stores and provides access to a
database. To
access data in a Web database, you fill in a form or enter search text on a Web
page, which is the front end to the database. A Web database usually resides on
a database server, which is a computer that stores and provides access to a
database. One type of program that manages the sending and receiving of data
between the front end and the database server is a CGI (Common Gateway
Interface) script.
9.
What Are the
Responsibilities of Database Analysts and Administrators?
·
A
database analyst (DA), or data modeler,
a.
Focuses
on the meaning and usage of data.
b.
The
DA decides on the placement of fields, defines data relationships, and
identifies users’ access privileges.
·
A database administrator (DBA) requires a more
technical inside view of the data. In small companies, one person often is both
the DA and DBA. In larger companies, the responsibilities of the DA and DBA are
split among two or more people.
The DBA is an IT
Professional that take care about
A.
Installation
To install a program to the company computer.
B.
Configuration
C.
Upgrade
Checks backup
and recovery procedures.
D.
Administration
E.
Monitoring
Monitors database
performance
F.
Maintenance
The DBA creates
and maintains the data dictionary
G.
Securing
Manages database
security
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