Kennesaw State University

Database Courseware Project(http://coffee.kennesaw.edu/)

Mario A.M. Guimaraes(mguimara@kennesaw.edu)

and Martha Myers

(mmyers@kennesaw.edu)

Database courseware (NSF)

• design and develop animations in support of key database concepts. Current topics

SQL (finished prototypes)

Database Design (few prototypes)

Concurrency (design, 1st prototype)

SQL Queries – prototypes available

• Visual Basic (downloadable)

Visualization

• Java (java applets)

Construction & Visualization

SQL Queries - motivation• Low student scores in tests involving

queries

• Construction: allows student to break SQL queries into parts and quickly access the results.

• Visualization: Associating code that students already know with code they are unfamiliar.

Database Design – prototype available (Flash)

• Convert E-R Diagrams to tables

1) Scenario

2) E-R Diagram is drawn

3) User is presented with several options

4) For each selected option, feedback, animating data redundancy and null

value is shown.

E-R Diagram -> Table – motivation

• Instructor may show several conversion options in a few minutes.

• Students memorize or are given the solution

(test results)

• Students have trouble detecting redundancy

Concurrency

• Lost Update (being implemented)

• Deadlock (being implemented)

The Lost Update:A Concurrency Problem

(table view)

Time 1Trx1 requests and receives a copy of X, 1000.

Time 2Trx2 requests and receives a copy of X, 1000.

Time 3

Trx1 decreases its value by 100 and returns the result (900) to the database.

Time 4

Trx2 increases the value 1000 by 200 and returns the new value (1200) to the database.

Deadlock

Trx1 requests and receives a copy of X, 1000.

Trx2 requests and receives a copy of Y, 2000.Trx2 requests a copy of X, and enters wait

Trx1 requests a copy of Y, and enters wait

Next Prototypes

• Database Design:

Class Diagrams

Object x Relational

Normalization

SQL Queries

Indexes: B-Trees, Hashing, Bitmap