Transcript Relational Operation Score

Kevin Pheasey
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Introduction
Related Work
How the language was implemented
Main concepts of query language
Test
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Majority of the database querying systems
developed for mobile access are for use on
PDAs
The systems only provide minimal querying
capabilities
Mostly pre-determined queries limits the use
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Support for different types of queries as well
as unplanned queries
Use Minimal Resources
Be easy to use given the restricted screen size
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Current query languages are restricted by the
domain of the application
◦ Hung and Zhang telemedicine system
◦ Kobayashi and Paungma transportation system
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Systems cannot be put on a mobile phone
because of a complex menu structure
Study shows users prefer direct input
opposed to a menu system
Menus are acceptable on a PDA where a
stylus is used
◦ Polyviou, Samaras and Evripidou implemented a
directory like interface
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33%
46%
Join
Union
Set Difference
16%
Projection
Selection
3% 2%
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Survey of 45
students
Created 3 queries
each of a University
database
Unplanned queries
still conformed to
the relational level
of query
expressiveness
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A relation that contains all other relations
(universal)
Different attributes must have different
names and the same attribute must have the
same name in every relation it‘s present
Useful in the normalization process
Reduces terms in query formation
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Lack of foreign keys
Use of precise terms
Minimal term ambiguity
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Relation names denote all attributes will be
displayed
Attribute name denotes the attribute will be
displayed
Conditions only in a query denote that all
attributes of the first relation tested will be
displayed
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STUDENT SUBJECT
SUBJECT.name STAFF.name
SUBJECT STAFF.name
STAFF.ID=112971 SUBJECT.crhr>3
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Prototype developed
on Java phone
emulator
Interface is drop
down menus
◦ interface for small
devices should be
simple and use as
many as possible highlevel APIs
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Created on Nokia
6681
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Part 1
◦ Pre-determined queries, allowed to ask for help
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Part 2
◦ Custom queries, allowed to ask for help
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Part 3
◦ Custom queries, no help, rated
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Part 4
◦ Pre-determined queries, no help, rated
Group #
Group 1
Group 2
Score
96.5%
97%
Relational
Operation
Score
Projection
100%
Selection
95.4%
Group 3
99%
Join (w/ out
condition)
99.2
Join (w/
condition)
98.1
Union/Set
Difference
100%
Groups’ Overall
Effectiveness Scores
Query Types’ Overall
Effectiveness Scores
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Creating a free-form query language for
mobile devices is possible
Free-form language eliminates the need for
Join and simplifies the number of query
inputs
Usability tests show the language is effective
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Rohiza Ahmad, Sameem Abdul-Kareem, "A
Free-Form Database Query Language for
Mobile Phones," 2009 WRI International
Conference on Communications and Mobile
Computing, January 2009, 279-284.