Chapter 1
Database Systems
LEARNING OBJECTIVES
• In this chapter, you will learn:
• The difference between data and information
• What a database is, the various types of databases,
and why they are valuable assets for decision making
• The importance of database design
• How modern databases evolved from file systems
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LEARNING OBJECTIVES
• In this chapter, you will learn:
• About flaws in file system data management
• The main components of the database system
• The main functions of a database management system
(DBMS)
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DATA VS. INFORMATION
DATA
INFORMATION
• Produced by processing
• Raw facts
• Raw
data - Not yet been
processed to reveal the
meaning
• Building
blocks
of
information
• Data management
• Generation,
storage, and
retrieval of data
data
• Reveals
the meaning of
data
• Enables knowledge creation
• Should
be
accurate,
relevant, and timely to
enable
good
decision
making
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DATABASE
• Shared,
integrated computer structure that stores a
collection of:
• End-user data - Raw facts of interest to end user
• Metadata: Data about data, which the end-user data are
integrated and managed
•
Describe data characteristics and relationships
• Database management system (DBMS)
• Collection of programs
• Manages the database structure
• Controls access to data stored in the database
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DATA IN CONTEXT
• Data
context is the network of connections
among data points. Those connections may be
created as metadata or simply identified and
correlated. Contextual metadata adds value,
essentially making it possible to receive information
from data. A single data point on its own is useless.
• Context helps users understand data.
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DATA IN CONTEXT
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SUMMARIZED DATA
BSIS Population by Academic Year
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Graphical displays turn data into useful information that
managers can use for decision making and interpretation
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EXAMPLE OF METADATA
Descriptions of the properties or characteristics of the data,
including data types, field sizes, allowable values, and data
context.
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YOU CAN HAVE DATA
“ WITHOUT
INFORMATION, BUT
YOU CANNOT HAVE
INFORMATION WITHOUT
DATA.
Daniel Keys Moran
”
TOP RELATIONAL DBMS
DBMS
RANKING as
of Feb. 2023
•
https://www.statista.co
m/statistics/809750/world
wide-popularity-rankingdatabase-managementsystems/
ROLE OF THE DBMS
• Intermediary between the user and the database
• Enables data to be shared
• Presents the end user with an integrated view of
the data
• Receives
and translates application requests into
operations required to fulfill the requests
• Hides
database’s internal complexity from the
application programs and users
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The DBMS Manages the Interaction between the
End User and the Database
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ADVANTAGES OF THE DBMS
• Better data integration and less data inconsistency
•
Data inconsistency: Different versions of the same data appear in
different places
• Increased end-user productivity
• Improved:
✓ Data sharing
✓ Data security
✓ Data access
✓ Decision making
✓
Data quality: Promoting accuracy, validity, and timeliness of data
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TYPES OF DATABASES (NUMBER OF USERS)
• Single-user database: Supports one user at a time
• Desktop database: Runs on PC
• Multiuser database: Supports multiple users at the
same time
• Workgroup databases: Supports a small number of
users or a specific department
• Enterprise database: Supports many users across many
departments
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TYPES OF DATABASES (LOCATION)
• Centralized database: Data is located at a single
site
• Distributed database: Data is distributed across
different sites
• Cloud database: Created and maintained using
cloud data services that provide defined
performance measures for the database
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TYPES OF DATABASES (EXPECTED TYPE)
• General-purpose
databases: Contains a wide
variety of data used in multiple disciplines
• Discipline-specific
databases: Contains
focused on specific subject areas
data
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TYPES OF DATABASES(EXTENT OF USE)
• Operational
database: Designed to support a
company’s day-to-day operations
• Analytical database: Stores historical data and
business metrics used exclusively for tactical or
strategic decision making
• Data warehouse: Stores data in a format optimized for
decision support
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TYPES OF DATABASES
• Online analytical processing (OLAP)
• Enable retrieving, processing, and modeling data
from the data warehouse
• Business
intelligence: Captures and processes
business data to generate information that
support decision making
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BASIC DATABASE TERMINOLOGY
• Data - raw facts, such as a telephone number, a birth
date, a customer name, and a year-to-date sales
value. Data have tittle meaning unless they have been
organized in some logical manner.
• Command
- is a string that you send to the server in
hopes of having the server do something useful. Some
people use the word statement to mean command. The
two words are very similar in meaning and, in practice,
are interchangeable.
• Query
- is a type of command that retrieves data
from the server.
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BASIC DATABASE TERMINOLOGY
• Table
(relation, file, class) - is a collection of rows. A table
usually has a name, although some tables are temporary and
exist only to carry out a command. All the rows in a table
have the same shape (in other words, every row in a table
contains the same set of columns). In other database systems,
you may see the terms relation, file, or even class
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BASIC DATABASE TERMINOLOGY
• Column (field, attribute) - is the
smallest unit of storage in a
relational database. A column
represents one piece of information
about an object. Every column has
a name and a data type. Columns
are grouped into rows, and rows
are grouped into tables.
• Row (record, tuple) - is a collection of column values. Every row in a table has the
same shape (in other words, every row is composed of the same set of columns). If
you are trying to model a real-world application, a row represents a real-world
object. For example, if you are running an auto dealership, you might have a
vehicles table. Each row in the vehicles table represents a car (or truck, or
motorcycle, and so on). The kinds of information that you store are the same for all
vehicles (that is, every car has a color, a vehicle ID, an engine, and so on).
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LEARNING ACTIVITIES
LEARNING ACTIVITIES.
1. List four applications you have used that most likely employed a database system to
store data.
_____________________________
_____________________________
_____________________________
_____________________________
LEARNING ACTIVITIES
LEARNING ACTIVITIES.
1. List four applications you have used that most likely employed a database system to
store data.
_____________________________
_____________________________
_____________________________
_____________________________
https://jamboard.google.com/d/1X1UjfD_xfvk3KJ5b2EzbogShTa_mSLWBO7Nzn2yokRs/edit?
usp=sharing
LEARNING ACTIVITIES
LEARNING ACTIVITIES.
2. Describe at least 3 tables that might be used to store information in a social
networking system such as Facebook.
_____________________________
_____________________________
_____________________________
LEARNING ACTIVITIES
LEARNING ACTIVITIES.
2. Describe at least 3 tables that might be used to store information in a social
networking system such as Facebook.
_____________________________
_____________________________
_____________________________
https://jamboard.google.com/d/1LTDvkE7zEojuqa_OYlUAXvSYBfJ3C73fGZQE_JFCKM/edit?usp=sharing
A SIMPLE FILE SYSTEM
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DATA INCONSISTENCY
• exists when different versions of the same data
appears in different places.
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DATA REDUNDANCY
• Data
Redundancy is a condition created within a
database or data storage technology in which the
same piece of data is held in two separate places.
• Islands of information: Scattered data locations
• Increases
the probability of having different versions
of the same data
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DATA REDUNDANCY IMPLICATIONS
• Poor data security
• Data inconsistency
• Increased likelihood of data-entry errors when
complex entries are made in different files
• Data
anomaly: Develops when not all of the
required changes in the redundant data are made
successfully
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DATA ANOMALY
• Anomalies are caused when there is too much redundancy in
the database's information. Anomalies can often be caused
when the tables that make up the database suffer from poor
construction. So, what does "poor construction" mean? Poor
table design will become evident if, when the designer
creates the database, he doesn't identify the entities that
depend on each other for existence, like the rooms of a hotel
and the hotel, and then minimize the chance that one would
ever exist independent of the other.
• The
normalization process was created largely in order to
reduce the negative effects of creating tables that will
introduce anomalies into the database.
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TYPES OF DATA ANOMALY
Update Anomalies
Insertion Anomalies
Deletion Anomalies
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TYPES OF DATA ANOMALY
• Insertion anomaly: The inability to store certain
attributes’ values without the other attributes. If we
are not able to insert a record into a relational
table because of the absence of values for other
attributes is called insertion anomaly.
TYPES OF DATA ANOMALY
• Deletion
anomaly: Deletion of values of certain
attributes from any records (rows) will lead to lose of
other attributes’ values of the same records. That
means, we lose the complete information about an
entity if we delete few values. This is called as
deletion anomaly.
• Modification of
certain values in a table may lead to
change the values in more than one record if that
particular value has duplicates. If we miss any one
occurrence of that data, that leads to inconsistency of
the table. This is called as modification anomaly.
SANA ALL…
THANKS!
Any questions?
You can find me at
delfirome@yahoo.com
0929 804 2327
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