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Instructors: Churee Techawut

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Chapter 1 Introduction to Database System Instructors: Churee Techawut CS (204)321 Database System I – PowerPoint PPT presentation

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Title: Instructors: Churee Techawut


1
Introduction to Database System
Chapter 1
lt PART 1 gt
  • Instructors Churee Techawut

CS (204)321 Database System I
2
Outlines
  • 1) Basic definitions
  • 2) Database system environment
  • 3) Typical DBMS functionality
  • 4) Examples of database
  • 5) Major characteristics of database approach
  • 6) Different types of database users
  • 7) Additional characteristics of database
    approach
  • 8) When not to use a DBMS
  • 9) Components of a database system
  • 10) Database system concepts and architecture

3
Basic Definitions
Mini-world Some part of the real world about
which data is stored in database e.g. student
grade and transcripts at a university.
Database Management System (DBMS) A software
package to facilitate the creation and
maintenance of a computerized database
Database system The DBMS software together with
the data itself. Sometimes, the applications are
also included.
4
Database System Environment
Users/Programmers
  • DATABASE
  • SYSTEM

Application Programs/Queries
DBMS SOFTWARE
Software to Process Queries/Programs
Software to Access Stored Data
Stored Database Definition (Meta-Data)
Stored Database
Source Elmasri R. Navathe S.B. (1994)
Fundamentals of database systems
5
Typical DBMS Functionality
  • Define a database
  • in terms of data types, structures and
    constraints
  • Construct or Load the Database on a secondary
    storage medium
  • Manipulating the database querying, generating
    reports, insertions, deletions and modifications
    to its content
  • Concurrent Processing and Sharing by a set of
    users and programs yet, keeping all data valid
    and consistent
  • Other features
  • - Protection or Security measures to prevent
    unauthorized access.
  • - Active processing to take internal actions on
    data.
  • - Presentation and Visualization of data

6
Examples of Database
  • A UNIVERSITY database for maintaining
    information concerning students, courses, and
    grades in a university environment.
  • To define this database, we must specify
  • The structure of the records.
  • For example, each STUDENT record includes data
    to
  • represent the students
  • Name,
  • StudentNumber,
  • Class (freshman or 1, sophomore or 2,), and
  • Major (MATH, computer science or COSC, ).

7
Examples of Database
  • A data type for each data element within record.
  • e.g.
  • Name of STUDENT is a string of alphabetic
    characters,
  • StudentNumber of STUDENT is an integer,
  • Grade of GRADE_REPORT is a single character from
    the set A,B,C,D,F,I,
  • Class of a STUDENT as 1 for freshman, 2 for
    sophomore, 3 for junior, 4 for senior, and 5 for
    graduate student.

8
Examples of Database
  • To construct the UNIVERSITY database, we store
    data to represent each student, course, section,
    grade report, and prerequisite as a record in the
    appropriate file. Records in the various files
    may be related to one another.
  • Database manipulation involves querying and
    updating. Example of query is retrieve all
    courses and grades of Smith.

9
Examples of Database
STUDENT Name StudentNumber Class Major
Smith 17 1 COSC
Brown 8 2 COSC
COURSE CourseName CourseNumber CreditHours Department
Intro to Computer Science COSC1310 4 COSC
Data Structures COSC3320 4 COSC
Discrete Mathematics MATH2410 3 MATH
Database COSC3380 3 COSC
PREREQUISITE CourseNumber PrerequisiteNumber
COSC3380 COSC3320
COSC3380 MATH2410
COSC3320 COSC1310
Source Elmasri R. Navathe S.B. (1994)
Fundamentals of database systems
10
Examples of Database
SECTION SectionIdentifier CourseNumber Semester Year Instructor
85 MATH2410 Fall 91 King
92 COSC1310 Fall 91 Anderson
102 COSC3320 Fall 92 Knuth
112 MATH2410 Fall 92 Chang
119 COSC1310 Fall 92 Anderson
135 COSC3380 Fall 92 Stone
GRADE_REPORT StudentNumber SectionIdentifier Grade
17 112 B
17 119 C
8 85 A
8 92 A
8 102 B
8 135 A
Source Elmasri R. Navathe S.B. (1994)
Fundamentals of database systems
11
Major Characteristics of Database Approach
Traditional file processing
Student fees
File
Student grades
File
Print student transcript and enter new grades
into the file.
Keep track of student fees and payments.
  • This redundancy in defining and storing data
    results in wasted storage space and in redundant
    efforts to maintain common data up-to-date.

12
Major Characteristics of Database Approach
Database approach
  • A single repository of data is maintained that
    is defined once and then is accessed by various
    users.

13
Major Characteristics of Database Approach
A traditional file processing can work with only
one specific database. The description of the
database is declared by data definition in the
application program. For example, C and C
program have struct or class declaration.
Changing in the structure of data files, embedded
in the access programs, requires to change all
programs that access this file.
14
Major Characteristics of Database Approach
In traditional file processing, the
representation of the structure of data files is
very complicated. Details that are not of
interest cannot be hidden.
A traditional file processing cannot provide a
different view of the database.
15
Major Characteristics of Database Approach
16
Different Types of Database Users
  • Workers on the scene

Persons whose job involves daily use of a large
database.
  • Database administrators (DBA)
  • Responsible for managing the database system
    authorizing, coordinating and monitoring.

2) Database designers Responsible for designing
the database identifying and choosing
appropriate structures.
3) End users The persons that use the database
for querying, updating, generating reports, etc.
17
Different Types of Database Users
3) End users The persons that use the database
for querying, updating, generating reports, etc.
There are several categories of end users. 3.1.
Casual end users They occasionally access the
database. 3.2. Naïve or parametric end users
They perform canned transaction. e.g. bank teller
or reservation clerk. 3.3. Sophisticated end
users They familiarize with DBMS and implement
complex applications. 3.4. Stand-alone users
They maintain personal database by using
ready-made program packages.
4) System analysts and application
programmers They determine requirements, design,
and implement canned transactions for parametric
user.
18
Different Types of Database Users
  • Workers behind the scene

Persons whose job involves design, development,
operation, and maintenance of the DBMS software
and system environment.
  • DBMS designers and implementers
  • Design and implement the DBMS modules and
    interfaces as a software package.

2) Tool developers Design and implement tools
that facilitate the use of DBMS software. Tools
include design tools, performance tools, special
interfaces, etc.
3) Operators and maintenance personnel They
responsible for the actual running and
maintenance of the hardware and software
environment for the database system.
19
Additional Characteristics of Database Approach
  • Controlling redundancy in data storage and in
    development and maintenance efforts.
  • Restricted unauthorized access to data.
  • Providing multiple interfaces to different types
    of users.
  • Representing complex relationships among data.
  • Enforcing integrity constraints on the database.
  • Providing backup and recovery services.
  • Potential for enforcing standard.
  • Flexibility to change data structures.
  • Reduced application development time.
  • Availability of up-to-date information.
  • Economies of scale.

20
When not to use a DBMS
  • Main costs of using a DBMS
  • High initial investment and possible need for
    additional hardware.
  • Overhead for providing generality, security,
    recovery, integrity, and concurrency control.
  • When DBMS may be unnecessary
  • If the database and applications are simple,
    well defined and not expected to change.
  • If there are stringent real-time requirements
    that may not be met because of the DBMS overhead.
  • If access to data by multiple users is not
    required.

21
Components of a Database System
  • Nine components of a typical database
    environment are as followings.

Source Hoffer, et al. (2002) Modern Database
Management.
22
Components of a Database System
  • Computer-aided software engineering (CASE) tools
  • Automated tools used to design databases and
    application programs.

2) Repository Centralized knowledge base for all
data definitions, data relationships, screen, and
report formats, and other system components.
3) DBMS A software system that is used to
create, maintain, and provide controlled access
to user databases.
4) Database The database contains a collection
of logically related data or occurrences of data.
5) Application programs Computer programs that
are used to create and maintain the database.
23
Components of a Database System
6) User interface Languages, menus, and other
facilities by which users interact with various
system components.
7) Data and database administrators Data
administrators are persons who are responsible
for the overall management of data resources in
an organization. Database administrators are
responsible for physical database design and for
managing physical issues in the database
environment.
8) System developers Persons who design new
application programs, such as system analysts and
programmers.
9) End users Persons who add, delete, and modify
data in the database and who request or receive
information.
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