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8/3/2019 Fundamental DB Concepts
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Advanced Database ConceptsISE-830 (3+0)
Fundamental Concepts
Instructor
Dr Sharifullah KhanSeptember 2011
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Advanced Database Concepts 2
Database System
Data recorded facts with implicit meaning
Database an integrated collection of data
preserved over a long period
organized for access and modification Data Base Management Systems (DBMS):
GENERALISED software package designed
to store and manage database
Defining, constructing and manipulating databases
Database System: database together with
DBMS
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Why Use Models?
Models can be useful when we want to
examine or manage part of the real world
The costs of using a model are often
considerably lower than the costs of using
or experimenting with the real world itself
Examples:
airplane simulator
nuclear power plant simulator
Advanced Database Concepts 3
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Data Model
Data abstraction hiding details of data
storage
A data model is a collection of concepts that
can be used to describe the structure of a
database:
Data structure, relationships and constraints
A data model provides the necessary meansto achieve this abstraction
Advanced Database Concepts 4
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Data Modeling
The model represents a perception of structures of
reality
The data modeling process is to fix a perception of
structures of reality and represent this perception
In the data modeling process we select aspects and
we abstract
Advanced Database Concepts 5
REALITY
structures
processes
DATABASE SYSTEM
MODEL
data modeling
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Advanced Database Concepts 6
Process Modeling
REALITY
structures
processes
DATABASE SYSTEM
MODEL
process modeling
The use of the model reflects processes of reality
Processes may be represented by programs with embedded
database queries and updates
Processes may be represented by ad-hoc database queries
and updates at run-timeDML DML
PROG
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Database Design
The purpose of database design is to create
a database which
is a model of structures of reality
supports queries and updates modeling
processes of reality
runs efficiently
Advanced Database Concepts 7
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Data Model
A data model consists of notations for
expressing:
data structures
integrity constraints
operations
Advanced Database Concepts 8
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Categories of Data Models
Conceptual data model High Level.
Entity-Relationship model.
Object data models.
Entity, attributes and relationship.
Representational data model.
Relational data model.
Record structure.
Physical data model Low Level. Record formats, record ordering and access path.
Advanced Database Concepts 9
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ER-Model
Data Structures
Integrity Constraints
Operations
The ER-Model is extremely successful as a database design
model
Translation algorithms to many data models
Commercial database design tools, e.g., ERwin
No generally accepted query language
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ER-Model - Data Structures
entity type
Relations
hip type
attribute
multivalued
attribute
derived
attribute
composite
attribute
subsetrelationshi
p type
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ER-Model - Integrity Constraints
A
E
E1 E3E2
RE1 E21 n
RE1 E2
RE1E2
(min,max)
RE1 E2R
cardinality: 1:n for E1:E2 in R
(min,max) participation of E2 in R
total participation of E2 in R
weak entity type E2; identifying
relationship type R
key attribute
d
op
disjoint
overlap
partition
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ER Model - Example
deptairport
date
internationalflight
domesticflight
p
flightinstance
flightschedule
instanceof
arrivairport
airport
1
n
n
1
street
depttime
airportcode
arrivtime
city zip
airportaddr
airportname
reserva-tion
nn
1
n
customer
flight#
customername
customer#
seat#
weekdays
visarequired
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ER-Model - Operations
Several navigational query languages have
been proposed
A closed query language as powerful asrelational languages has not been developed
None of the proposed query languages has
been generally accepted
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Relational Model
Data Structures
Integrity Constraints
Operations
Commercial systems include: ORACLE,DB2, SYBASE, INFORMIX, INGRES, SQL
Server
Dominates the database market on allplatforms
Advanced Database Concepts 15
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Advanced Database Concepts 16
Relational Model - Data Structures
domains
attributes
relations
flight-scheduleflight#:
integer
airline:
char(20)
weekday:
char(2)
price:
dec(6,2)
relation name
attribute
names
domain names
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Advanced Database Concepts 17
Relational Model - Integrity Constraints
Keys
Primary Keys
Entity Integrity
Referential Integrity
reservation
flight# date customer#
flight-schedule
flight#
p
customer
customer# customer name
p
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Relational Model - Operations
Powerful set-oriented query languages
Relational Algebra: procedural; describes
how to compute a query; operators likeJOIN, SELECT, PROJECT
Relational Calculus: declarative; describes
the desired result, e.g. SQL, QBE
insert, delete, and update capabilities
Advanced Database Concepts 18
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Advanced Database's Concepts 19
Normalization
FLIGHT# AIRLINE PRICE
FLIGHT-SCHEDULE
101 delta 156
545 american 110
912 scandinavia
n
450
FLIGHT# AIRLINE WEEKDAY PRICE
FLIGHT-SCHEDULE
101 delta mo
545 american mo 110
912 scandinavian fr 450
156
101 delta fr 156545 american we 110545 american fr 110
FLIGHT# AIRLINE WEEKDAYS PRICEFLIGHT-SCHEDULE
101 delta mo,fr 156
545 american mo,we,fr 110
912 scandinavian fr 450
FLIGHT# WEEKDAY
FLIGHT-WEEKDAY
101 mo
545 mo
912 fr
101 fr
545 we
545 fr
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Advanced Database's Concepts 20
Schemas, Instances and Data State
Schema description of a database.
Frequently changes are unexpected.
Schema construct STUDENT, COURSE.
Instances entities (records) of individualschema construct.
Frequently changed
Data state data at a particular moment intime
Current set of instances.
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Advanced Database's Concepts 21
Instances and Data State
Student
Name Student Number Class Major
Karim 17 1 CS
Naeem 8 2 CS
Course
CourseName CourseNo CreditHours Departmen
t
Intro to Comp Science CS1310 4 CS
Data Structure CS3320 4 CSDiscrete Mathematics MATH2410 3 MATH
Database CS3380 3 CS
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Advanced Database's Concepts 22
Three-Schema Architecture
Internal Schema
Conceptual Schema
External View External View
End users
Stored Databases
Conceptual/internal mapping
External/conceptual
mapping
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Advanced Database Concepts 23
Data Independence
Logical data independence:
Logical data independence is a measure of how
much the conceptual schema can change without
affecting the application programs Physical data independence:
Physical data independence is a measure of how
much the internal schema can change without
affecting the application programs
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Advanced Database Concepts 24
DBMS Languages
Data Definition Language (DDL).
Data Manipulation Language (DML).
Non procedural DML high level.
Set-at-a-time.
Procedural DML low level.
Record-at-a-time.
Query Language High level DML, e.g.
SQL.
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Advanced Database Concepts 25
Classification of DBMSs -I
Data model:
Relational DBMSs.
Object DBMSs. Object-relational DBMSs.
Number of users:
Single-user systems.
Multi-user systems.
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Advanced Database Concepts 26
Classification of DBMSs - II
Number of Sites:
Centralized DBMSs.
Distributed DBMSs (DDBMSs). Homegeneous DDBMSs.
Hetrogeneous DDBMSs.
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Advanced Database Concepts 27
The End
Thanks for Your Attention
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