Chapter01.ppt.dbms.talles,rows,columns,data

CHAPTER 1
Databases and Database Users
Slide 1- 2

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OUTLINE
 Types of Databases and Database Applications
 Basic Definitions
 Typical DBMS Functionality
 Example of a Database (UNIVERSITY)
 Main Characteristics of the Database Approach
 Types of Database Users
 Advantages of Using the Database Approach
 Historical Development of Database Technology
 Extending Database Capabilities
 When Not to Use Databases

What is data, database, DBMS
 Data: Known facts that can be recorded and have an implicit meaning;
raw
 Database: a highly organized, interrelated, and structured set of data
about a particular enterprise

Controlled by a database management system (DBMS)
 DBMS

Set of programs to access the data
 An environment that is both convenient and efficient to use
 Database systems are used to manage collections of data that are:
 Highly valuable
 Relatively large
 Accessed by multiple users and applications, often at the same time.
 A modern database system is a complex software system whose task is
to manage a large, complex collection of data.
 Databases touch all aspects of our lives
Slide 1- 4

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Types of Databases and
Database Applications
 Traditional applications:
 Numeric and textual databases
 More recent applications:
 Multimedia databases
 Geographic Information Systems (GIS)
 Biological and genome databases
 Data warehouses
 Mobile databases
 Real-time and active databases
 First part of book focuses on traditional applications
 A number of recent applications are described later in the
book (for example, Chapters 24,25,26,27,28,29)

Recent Developments (1)
 Social Networks started capturing a lot of
information about people and about
communications among people-posts, tweets,
photos, videos in systems such as:
- Facebook
- Twitter
- Linked-In
 All of the above constitutes data
 Search Engines, Google, Bing, Yahoo: collect their
own repository of web pages for searching
purposes
Slide 1- 6

Recent Developments (2)
 New technologies are emerging from the so-
called non-SQL, non-database software vendors
to manage vast amounts of data generated on
the web:

Big data storage systems involving large clusters
of distributed computers (Chapter 25)

NOSQL (Non-SQL, Not Only SQL) systems (Chapter
24)
 A large amount of data now resides on the “cloud”
which means it is in huge data centers using
thousands of machines.
Slide 1- 7

What is “big data”?
 "Big data are high-volume, high-velocity, and/or
high-variety information assets that require new
forms of processing to enable enhanced decision
making, insight discovery and process optimization”
(Gartner 2012)
 Three Vs? Other Vs?

Veracity: refers to the trustworthiness of the data

Value: will data lead to the discovery of a critical causal
effect?
 Bottom line: Any data that exceeds our current
capability of processing can be regarded as “big”
 Complicated (intelligent) analysis of data may make a
small data “appear” to be “big”

Why is “big data” a “big deal”?
 Government
 Private Sector
 Walmart handles more than 1 million customer
transactions every hour, which is imported into
databases estimated to contain more than 2.5
petabytes of data
 Facebook handles 40 billion photos from its user base
 Falcon Credit Card Fraud Detection System protects
2.1 billion active accounts world-wide
 Science
 Large Synoptic Survey Telescope will generate 140
Terabyte of data every 5 days
 Biomedical computation like decoding human
Genome and personalized medicine

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Basic Definitions
 Database:
 A collection of related data.
 Data:
 Known facts that can be recorded and have an implicit meaning.
 Mini-world:
 Some part of the real world about which data is stored in a
database. For example, student grades and transcripts at a
university.
 Database Management System (DBMS):
 A software package/system 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.

Impact of Databases and
Database Technology
 Businesses: Banking, Insurance, Retail,
Transportation, Healthcare, Manufacturing
 Service industries: Financial, Real-estate, Legal,
Electronic Commerce, Small businesses
 Education : Resources for content and Delivery
 More recently: Social Networks, Environmental
and Scientific Applications, Medicine and
Genetics
 Personalized applications: based on smart
mobile devices
Slide 1- 11

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A simplified architecture for a
database system
Physical level:
describes how a
record (e.g.,
instructor) is
stored.
View level: what application
programs see; views can also
hide information (such as an
instructor’s salary) for security
purposes.

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database system

14
database system

database system
Slide 1- 15

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What a DBMS Facilitates
 Define a particular database in terms of its data types,
structures, and constraints
 Construct or load the initial database contents on a
secondary storage medium
 Manipulating the database:

Retrieval: Querying, generating reports

Modification: Insertions, deletions and updates to its
content

Accessing the database through Web applications
 Processing and sharing by a set of concurrent users and
application programs – yet, keeping all data valid and
consistent

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Other DBMS Functionalities
 DBMS may additionally provide:
 Protection or security measures to prevent
unauthorized access
 “Active” processing to take internal actions on
data
 Presentation and visualization of data
 Maintenance of the database and associated
programs over the lifetime of the database
application

Application Programs and DBMS
 Applications interact with a database by
generating
- Queries: that access different parts of data and
formulate the result of a request
- Transactions: that may read some data and
“update” certain values or generate new data
and store that in the database
Slide 1- 18

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Example of a Database
(with a Conceptual Data Model)
 Mini-world for the example:
 Part of a UNIVERSITY environment
 Some mini-world entities:
 STUDENTs
 COURSEs
 SECTIONs (of COURSEs)
 (Academic) DEPARTMENTs
 INSTRUCTORs

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Example of a Database
(with a Conceptual Data Model)
 Some mini-world relationships:
 SECTIONs are of specific COURSEs
 STUDENTs take SECTIONs
 COURSEs have prerequisite COURSEs
 INSTRUCTORs teach SECTIONs
 COURSEs are offered by DEPARTMENTs
 STUDENTs major in DEPARTMENTs
 Note: The above entities and relationships are typically
expressed in a conceptual data model, such as the
entity-relationship (ER) data or UML class model (see
Chapters 3, 4)

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Example of a Simple Database

The relational model
Slide 1- 22
E.F. “Ted” Codd

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Main Characteristics of the
Database Approach
 Self-describing nature of a database system:
 A DBMS catalog stores the description of a particular
database (e.g. data structures, types, and constraints)

The description is called meta-data*.

This allows the DBMS software to work with different
database applications.
 Insulation between programs and data:

Called program-data independence.
 Allows changing data structures and storage organization
without having to change the DBMS access programs

E.g., ADTs

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Example of a Simplified Database
Catalog

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Database Approach (continued)
 Data abstraction:
 A data model is used to hide storage details
and present the users with a conceptual view
of the database.
 Programs refer to the data model constructs
rather than data storage details
 Support of multiple views of the data:
 Each user may see a different view of the
database, which describes only the data of
interest to that user.

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 Sharing of data and multi-user transaction
processing:
 Allowing a set of concurrent users to retrieve from and
to update the database.
 Concurrency control within the DBMS guarantees that
each transaction is correctly executed or aborted
 Recovery subsystem ensures each completed transaction
has its effect permanently recorded in the database
 OLTP (Online Transaction Processing) is a major part of
database applications; allows hundreds of concurrent
transactions to execute per second.

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Database Users
 Users may be divided into
 Those who actually use and control the
database content, and those who design,
develop and maintain database applications
(called “Actors on the Scene”), and
 Those who design and develop the DBMS
software and related tools, and the computer
systems operators (called “Workers Behind the
Scene”).

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Database Users – Actors on the
Scene
 Actors on the scene

Database administrators

Responsible for authorizing access to the database,
for coordinating and monitoring its use, acquiring
software and hardware resources, controlling its
use and monitoring efficiency of operations.

Database designers

Responsible to define the content, the structure,
the constraints, and functions or transactions
against the database. They must communicate with
the end-users and understand their needs.

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Database End Users
 Actors on the scene (continued)
 End-users: They use the data for queries, reports
and some of them update the database content.
End-users can be categorized into:

Casual: access database occasionally when needed

Naïve or parametric: they make up a large section of
the end-user population.
 They use previously well-defined functions in the form of
“canned transactions” against the database.
 Users of mobile apps mostly fall in this category
 Bank-tellers or reservation clerks are parametric users who
do this activity for an entire shift of operations.
 Social media users post and read information from
websites

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Database End Users (continued)
 Sophisticated:

These include business analysts, scientists, engineers,
others thoroughly familiar with the system capabilities.
 Many use tools in the form of software packages that
work closely with the stored database.
 Stand-alone:

Mostly maintain personal databases using ready-to-use
packaged applications.

An example is the user of a tax program that creates its
own internal database.
 Another example is a user that maintains a database of
personal photos and videos.

Database Users – Actors on the
Scene (continued)
 System analysts and application developers

System analysts: They understand the user
requirements of naïve and sophisticated users and
design applications including canned transactions to
meet those requirements.

Application programmers: Implement the
specifications developed by analysts and test and
debug them before deployment.

Business analysts: There is an increasing need for such
people who can analyze vast amounts of business data
and real-time data (“Big Data”) for better decision
making related to planning, advertising, marketing etc.
Slide 1-
31

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Database Users – Actors behind
the Scene
 System designers and implementors: Design and
implement DBMS packages in the form of modules and
interfaces and test and debug them. The DBMS must interface
with applications, language compilers, operating system
components, etc.
 Tool developers: Design and implement software systems
called tools for modeling and designing databases,
performance monitoring, prototyping, test data generation, user
interface creation, simulation etc. that facilitate building of
applications and allow using database effectively.

Operators and maintenance personnel: They manage
the actual running and maintenance of the database system
hardware and software environment.

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Advantages of Using the
Database Approach
 Controlling redundancy in data storage and in
development and maintenance efforts.
 Sharing of data among multiple users.
 Restricting unauthorized access to data. Only the
DBA staff uses privileged commands and
facilities.
 Providing persistent storage for program Objects
 E.g., Object-oriented DBMSs make program
objects persistent– see Chapter 12.
 Providing storage structures (e.g. indexes) for
efficient query processing – see Chapter 17.

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Advantages of Using the
 Providing optimization of queries for efficient
processing
 Providing backup and recovery services
 Providing multiple interfaces to different classes
of users
 Representing complex relationships among data
 Enforcing integrity constraints on the database
 Drawing inferences and actions from the stored
data using deductive and active rules and triggers

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Additional Implications of Using
the Database Approach
 Potential for enforcing standards:
 Standards refer to data item names, display
formats, screens, report structures, meta-data
(description of data), Web page layouts, etc.
 Reduced application development time:
 Incremental time to add each new application is
reduced.

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Additional Implications of Using
the Database Approach
(continued)
 Flexibility to change data structures:
 Database structure may evolve as new
requirements are defined.
 Availability of current information:

Extremely important for on-line transaction
systems such as shopping, airline, hotel, car
reservations.
 Economies of scale:

Wasteful overlap of resources and personnel can be
avoided by consolidating data and applications
across departments.

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Historical Development of
Database Technology
 Early database applications:
 The Hierarchical and Network models were introduced in
mid 1960s and dominated during the seventies.
 A bulk of the worldwide database processing still occurs
using these models, particularly, the hierarchical model
using IBM’s IMS system.
 Relational model-based systems:
 Relational model was originally introduced in 1970, was
heavily researched and experimented within IBM
Research and several universities.
 Relational DBMS Products emerged in the early 1980s.

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Database Technology
(continued)
 Object-oriented and emerging applications:
 Object-Oriented Database Management Systems
(OODBMSs) were introduced in late 1980s and early
1990s to cater to the need of complex data processing in
CAD and other applications.

Their use has not taken off much
 Many relational DBMSs have incorporated object
database concepts, leading to a new category called
object-relational DBMSs (ORDBMSs)
 Extended relational systems add further capabilities (e.g.
for multimedia data, text, XML, and other data types)

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Database Technology
(continued)
 Data on the Web and e-commerce applications:
 Web contains data in HTML (Hypertext markup
language) with links among pages
 Has given rise to a new set of applications and
E-commerce is using new standards like XML
(eXtended Markup Language) (see Ch. 13).
 Script programming languages such as PHP and
JavaScript allow generation of dynamic Web
pages that are partially generated from a
database (see Ch. 11).

Also allow database updates through Web pages

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Extending Database Capabilities
(1)
 New functionality is being added to DBMSs in the
following areas:
 Scientific applications – physics, chemistry, biology,
genetics
 Spatial: weather, earth and atmospheric sciences
and astronomy
 XML (eXtensible Markup Language)
 Image storage and management
 Audio and video data management
 Time series and historical data management
 The above gives rise to new research and development
in incorporating new data types, complex data
structures, new operations and storage and indexing
schemes in database systems.

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When not to use a DBMS
 Main inhibitors (costs) of using a DBMS:
 High initial investment and possible need for additional
hardware

Overhead for providing generality, security, concurrency
control, recovery, and integrity functions
 When a DBMS may be unnecessary:

If the database and applications are simple, well defined,
and not expected to change

If access to data by multiple users is not required
 When a DBMS may be infeasible
 In embedded systems where a general-purpose DBMS
may not fit in available storage

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When not to use a DBMS
 When no DBMS may suffice:

If there are stringent real-time requirements
that may not be met because of DBMS
overhead (e.g., telephone switching systems)

If the database system is not able to handle the
complexity of data because of modeling
limitations (e.g., in complex genome and protein
databases)

If the database users need special operations not
supported by the DBMS (e.g., GIS and location-
based services).

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Chapter Summary
 Types of databases and database applications
 Basic definitions
 Typical DBMS functionality
 Example of a database (UNIVERSITY)
 Main characteristics of the database Approach
 Types of database users
 Advantages of using the database approach
 Historical development of database technology
 Extending database capabilities
 When not to use databases

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