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INTRO TO DATABASES PART II

IS 340

BY

CHANDRA S. AMARAVADI

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DBMS evolution file processing, hierarchical, relational

ER Models Distributed databases Multi-media databases Data warehouses

IN THIS PRESENTATION..

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DBMS EVOLUTION

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EVOLUTION OF DBMS

File processingsystems

Hierarchicalsystems

Relationalsystems

1 March 2002 Greece2 July 2003 Italy3 ……………..

Person

Photo1 Photo2

Greece Italy

PhotoId

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EVOLUTION OF DBMS..FILE PROCESSING SYSTEMS:

Data in the form of “flat files” (ascii files) Each program had its own specific files Data was duplicated across files.

A system where data was managed by the programin the form of flat files.

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EVOLUTION OF DBMS..PROBLEMS CAUSED BY FILE PROCESSING

Uncontrolled redundancy Poor data quality (a.k.a.?) Lack of data sharing

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HIERARCHICAL MODEL

structure is hierarchical (not flat) one or more root segments child segments are linked hierarchically

difficult to write queries but very efficient (fast)!

A model for storing data:

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HIERARCHICAL MODEL

NAME TOTAL_ENROLL NO_OF_PHD

ASNAME JOB_TITLE FNAME RANK DEGREE

(D) DEPARTMENT

(A) ADMIN-STAFF (F) FACULTY

What do you call this?

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Data organized into tablesData retrieved by using SQL, 4th GL

joins tables by equating values of cross reference keys.

RELATIONAL MODEL

8895 Smith 4/16/00 $35,000

8896 Farley 4/22/01 $300

8897 Gomez 1/10/00 $2,000

ACCT

ACCT# NAME DT. OPENED BALANCE

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ER MODELS (Data Models)

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DEFINITIONSEntity – Individual example of person, place or thing.Entity Class – Collection of related entities.Attributes – Properties of entity classes about which we would like to collect information.

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AN EXAMPLE ER CHART

CUSTOMER

ORDERS

places

Cust# Name

PRODUCTSare for

ENTITY CLASS

ATTRIBUTE

RELATIONSHIP

Ord# Ord dt

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Draw Data Models (ER models) corresponding to the followingSituations:

Athletes participate in events (qualifier, semi-finals, finals) in various sports (swimming, boxing etc.).

Clients can book one or more properties with a rental agency. Eachproperty can be booked by more than one client (for different dates).

Trains arrive and depart from platforms in train stations, corresponding to the cities that they stop in. A city can have many Stations.

Airlines operate a number of flights which arrive and depart fromGates. There could be several flights from a gate, but each flightis assigned only one gate. Each airline operates a gate or a set of Gates which are leased to them by the airport.

DISCUSSION

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Design a database for the following situation: Bellsouth, atelephone company needs a database to maintain records ofits automobiles, repairs, mechanics and special equipment neededto repair cars. Mechanics are assigned skill codes based on thetype of repairs they can carry out. For e.g. Class III mechanicscan perform reborings, engine overhauls and transmission repairs.The repair shops are located in 300 cities and towns throughout the state. Mechanics can be assigned to only one repair shop at atime. The application requires knowing what equipment is (fore.g. diagnostic equipment, hydraulic machinery) is at what locationand also the repairs carried out on each vehicle. For each vehiclethe application requires knowing its identification number, mileage and repair history.

DISCUSSION

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DISTRIBUTED ANDMULTI-MEDIA DATABASES,

DATA WAREHOUSES

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CENTRALIZED DATABASES

The database is in one physical location. All applications regardless of whether the clients are located in Seoul or Detroit need to access data from that physical location. What are the limitations?

Centralized databases

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DISTRIBUTED DATABASES

Replicated -- copies of the database maintained in multiple sites Partitioned -- database is physically divided into chunks

The data is physically stored in multiple geographical locations

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REPLICATED DATABASES..

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PARTITIONED DATABASES..

Emp ID Emp Name Emp Address

11049 Richard 200 Meadow brook

11051 Cathy 13 E. Willow

11054 Hugh 1400 E. Washington

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MULTI-MEDIA DATABASES

Emp ID Emp Name Emp. Picture Emp Address

A database that is able to handle multiple data types: Conventional information Images Audio & video

Capable of storing, retrieving and updating this type ofinformation

Emp.jpg

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MULTI-MEDIA DATABASES..

APPLICATIONS

Travel bureaus Hospitals Manufacturing Training

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MULTI-MEDIA DATABASES..

Storage space Retrieval Modification

ISSUES

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DATA WAREHOUSE: Historical data organized for analysis and decision making.

DATA MART: smaller version of data warehouse, specialized by

functional area e.g. marketing

ON-LINE ANALYTICAL PROCESSING (OLAP): organizes data into a “cube” for decision analysis.

DATA WAREHOUSES

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HISTORICALINFORMATION

INTERNALDATASOURCES

EXTERNALDATASOURCES

OPERATIONAL,HISTORICAL DATA

DATA WAREHOUSE

EXTRACT,TRANSFORM

OLAP

DATA MINING

DATA WAREHOUSING & OLAP

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DISCUSSION QUESTIONS

Are Databases and DBMSs one and the same? Does a record consist of files? What is the smallest unit of data in the database? Does data integrity refer to data quality? What does the detail line of a report consist of? Is an “employee” an entity class or an attribute? Is the data dictionary useful while creating the database? Why do we use SQL? Is it necessary to use SQL to produce database reports? Why do we use data models? Would multi-national organizations prefer centralized databases?

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THAT’S ALL FOLKS!