Fundamentals of Database system - Databases and Database Users

Fundamentals of Database systems
Ministry of Higher Education
Bamyan University
Computer Science Department
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Presented by : Mustafa Kamel Mohammadi
Email : bamian.cs@gmail.com
Databases and Database Users
Fundamentals of database system 6th edition

Agenda of course
 Database design and implementation
 Database systems introduction and concepts
 Database system architecture
 Relational Database design
 Relational algebra
 SQL
 ER modeling
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learning objective
 In this chapter you will learn
 Introduction to database systems
 Database size and complexity
 What is DBMS?
 Characteristics of Database approach
 Users of database
 Advantages of using database system
 Database systems evolution
 When not to use database systems
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Introduction
 Databases and database systems are an essential component of life in modern
society and used in different fields
 Schools
 Universities
 Online marketing
 Airline reservation
 Digital Libraries
 Markets
 Inventories
 Companies
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Introduction (cont..)
 ERP (Enterprise Resource Planning) systems
 HR (Human resource)
 Finance
 Costumer relationship
 Supply
 Hospitals
 Geographical org
 Weather predictions
 Communication
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Types of Database systems
 Traditional database
 information that is stored and accessed is either textual or numeric
 Multimedia databases
 store images, audio clips, and video streams digitally
 Geographic information systems
 can store and analyze maps, weather data, and satellite images
 Data warehouses and online analytical processing (OLAP) systems
 Extract and analyze useful business information from very large databases to support
decision making
 Real-time and active database technology
 used to control industrial and manufacturing processes
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Definition
 A Database is a collection of logically related data
 Data = facts that can be recorded and that have implicit meaning like names, telephone
numbers, and addresses of the people
Database properties
 Represents some aspect of the real world.
 Database is a mini world.
 Designed, built, and populated with data for a specific purpose.
 It has some group of users and applications that use database.
 Has degree of interaction through application
 User is actively interested in it’s content
 Has source from which data is derived
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Size and Complexity
 A Database can be of any size and complexity
 According to size
 As small to store few hundreds of records like a contact list
 As big like Google ….
 According to complexity
 Less complex like a simple insertion and retrieval system
 More complex like amazon, Facebook , financial systems
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DBMS (Database management system)
 A collection of programs that enables users to create and maintain a database.
 It Manages Database files the same as “Windows Explorer” manages files in
Drives.
 A General-purpose software system that facilitates the
 Defining
 Involves specifying the data types, structures, and constraints of the data
 Constructing
 the process of storing the data on some storage medium
 Manipulating
 Retrieving , updating, deleting records
 Sharing
 allows multiple users and programs to access the database simultaneously
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Cont.
 Other functions of DBMS
 Protection : protecting against hardware and software malfunction
 Security : protecting against unauthorized access
 Maintaining : allow the system to evolve as requirements change over time
 Application program accesses the database by sending queries or requests for
data to the DBMS
 Query typically causes some data to be retrieved
 Database and DBMS software together a Database System
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Characteristics of Database approach
1-Self-Describing Nature of a Database System
The database system contains not only the data itself but also a complete
definition
Definition is stored in the DBMS catalog
 Information such as the structure of each file, the type and storage format of each data item,
and various constraints on the data
The information stored in the catalog is called meta-data
In traditional file processing, data definition is typically part of the application
programs themselves
DBMS software refers to the catalog to determine the structure of the database
elements
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Cont.
2-Insulation between Programs and Data , and Data Abstraction
In file processing, changes to the structure of a file may require changing all
programs that access that file
In database approach changes in database may not require changes in application
level
We call this property program-data independence
In object oriented approach operations are also defined which causes program
operation independence
The characteristic that allows program-data independence and program-
operation independence is called Data abstraction
 hides storage and implementation details from most database users
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Cont.
3-Support of Multiple Views of the Data
A Database typically has many users, each of whom may require a different view
of the database
A view may be a subset of the database
It may contain virtual data that is derived but not explicitly stored.
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Cont.
4-Sharing of Data and Multiuser Transaction Processing
Sharing allow multiple users to access the database at the same time
 The DBMS must include concurrency control software
Transaction is an executing program or process that includes one or more
database accesses
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Actor of Database
 Small database
 one person typically defines, constructs, and manipulates the database, and there maybe no
sharing
 Large scale database
 many people are involved in the design, use, and maintenance of a large database with
hundreds of users with different responsibilities
 Actors on the scene
 people whose jobs involve the day-to-day use of a large database
 Workers behind the scene
 those who work to maintain the database system environment but who are not actively
interested in the database contents
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Actors on the Scene
 Database designer
 Communicate with all database users to understand their requirements
 Responsible for identifying the data to be stored in the database
 Choosing appropriate structures to represent and store this data
 Develop views of the database that meet the data and processing requirements
 Database administrator
 Manage primary and secondary resource ( Database and DBMS software)
 Authorizing access to the database
 Monitoring its use
 Acquiring software and hardware resources as needed
 Fix security gaps and poor system response time
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Cont.
End users:
Casual end users
 Occasionally access database but use a sophisticated database query language
 Middle or high-level managers
Naive end users
 Using standard types of queries and update called canned transactions
Sophisticated end users
 Are familiar with Database Queries or Database Languages
 Like engineers, scientists, business analysts.
 Standalone users
 Using ready-made program packages that provide easy-to-use menu-based or graphics-
based interfaces
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Cont.
System Analyst
 System analysts determine the requirements of end users
Application Programmers
 Application programmers implement these specifications as programs
 They test, debug, document, and maintain database transactions.
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Actors behind the Scene
DBMS designer and implementers
Design and implement the DBMS modules and interfaces
Tool developers
design and implement tools
 software packages that facilitate database modeling and design, performance monitoring ….
Operators and maintenance personnel
responsible for the actual running and maintenance of
 hardware
 software
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Advantages of using Database
1-Controlling Redundancy
In traditional file processing every user of the system has his/her own file
independently for recording data
 Some data might be recorded multiple times in different places.
Redundancy (storing the same data multiple times) leads to several problem
 Duplication of operation
 Storage space is wasted
 Inconsistency
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Cont.
2-Restricting Unauthorized Access
When multiple users share a large database, most users will not be authorized to
access all information in the database
 Retrieval
 Deletion
 Update
 DBMS should provide a security and authorization subsystem
 DBA create accounts and to specify account restrictions
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Cont.
3-Providing Persistent Storage for Program Objects
The main reasons for object-oriented database systems
Two types of object
 Transient objects
 Persistent objects
Object oriented DBMSs transform transient object to persistent
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Cont.
4-Providing Storage Structures and Search Techniques for Efficient Query
Processing
Database systems must provide capabilities for efficiently executing queries and
updates by
 Specialized data structures
 Search techniques to speed up disk search
5-Providing Backup and Recovery
Must provide facilities for recovering from hardware or software failures
Backup and recovery subsystem of the DBMS is responsible
 Recovery by transactions
 In case of failure in query processing
 Disk backup and recovery
 In case of disk failure
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Cont.
6-Representing Complex Relationships among Data
database may have too much entities that can have complex an numerous
relationship with each other
A DBMS must have the capability to
 Define relationship between entities
 Retrieve data according to specified relationship
7-Providing Multiple User Interfaces
DBMS should provide a variety of user interfaces for group of users
 Query languages interface
 Programming language interfaces for application programmers
 Forms
 menu-driven interfaces
known as graphical user interfaces (GUIs)
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Cont.
8-Enforcing Integrity Constraints by :
 Specifying a data type for each data item
 Key or uniqueness constraint
 Business rules
9-Permitting Inference and Actions Using Rules
Deductive database systems
 Capabilities for defining deduction rules for inferring new information from the stored
database facts
Active database systems
 Automatically initiate actions when certain events and conditions occur.
 Triggers and events
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Cont.
Additional implications for using database approach
Potential for Enforcing Standards
Reduced Application Development Time
Flexibility
Availability of Up-to-Date Information
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History and evolution of Database systems
Network and hierarchical systems
Relational Databases
Object-Oriented Applications and the Need for More Complex Databases
Interchanging Data on the Web for E-Commerce Using XML
Extending Database Capabilities for New Applications
 Scientific applications
 Storage and retrieval of images and videos
 Data mining applications and analyzing large amounts of data
 Spatial applications that store spatial locations of data … GIS,GPS
 Time series applications
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When Not to Use a DBMS
The overhead costs of using a DBMS are due to the following
High initial investment in hardware, software, and training
The generality that a DBMS provides for defining and processing data
Overhead for providing security, concurrency control, recovery
Use regular files under the following circumstances
Simple, well-defined database applications that are not expected to change at all
Embedded systems with limited storage capacity
No multiple-user access to data
Real-time requirements for some application programs that may not be met
because of DBMS overhead
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Exercise
• Discuss the main characteristics of the Database approach and how it differs from
traditional file systems.
• What are the responsibilities of the DBA and the database designers?
• Email: bamian.cs@gmail.com
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