digital transmission lecture 1

7/25/2019 Digital Transmission Lecture 1

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Content of INFR 3810

! Design of databases.

!

E/R model, Design by Decomposition, (UML, ODL),

semi-structured model such as XML.

! Relational algebra.

! SQL

!

Improving the performances

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Syllabus

! Instructor office hours: Thursdays 9:30 11:00 am

! Skpe account: wei_classesTA Skype account:robert.burden-ta

! Textbook

! Assignments

! Exams

! late assignment policy

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Evaluation Scheme1.

Final:! 40% in total

2.

Homeworks:! 3 assignments

! Individual

! 30% in total

3.

Inclass Participations:! Hands-on exercises in almost every lecture

!

10% in total

4.

Quizzes! 20% in total

! 4 Blackboard quizzes + 1 in-class quiz4


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Scenarios

! A company wishes to store and access informationabout its employees, departments, and projects.

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Scenarios

! Students (and Instructors) would like to know howassignment marking is progressing.

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File Systems as Database

! We can write programs

!

open disk files, write to files, and close files

!

store data and retrieve it from the appropriate files

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...File Systems as Database

! What does disk files support?

!

Data lives a long time

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! Goal: creating a new database of student marks

! soln: create a new file, decide on the format of data,

write programs which access data based on known

format

! Problems:

! data format

!

data is probably duplicated

!

data schema

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! Goal: query the database to print names of studentswith A+

! soln: write a method to search file for students with

mark=A+

! Problems:

!

query!

new queries

!

query optimization

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! Goal: Data should be free of inconsistencies (Youcannot get a B and A- in the same course)

! soln: make sure procedures verify data is valid

! Problems:

! integrity constraints

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! Goal: Data should be secure from unauthorized users

! soln: use file access permissions

! Problems:

!

file access permission

!

file access restrictions

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! Goal: Data should be usable by several usersconcurrently (Two agents book a seat on a plane

simultaneously)

! soln: Custom locking code

! Problems:

! locking code

!

basic concurrency control

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! Goal: Data invariants must be maintained (During anaccount transfer the power fails after the withdrawal

but before the deposit)

! soln: no easy solution

! Problems:

!

program failure

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Database Solution

! Use an application to which we input:

!

data

!

Constraints

!

arbitrary queries

!

access controls

!

modification of data

! transaction control

! The database is generic -works with anyones data orqueries -at run time

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We will Study

! Database modeling and design

!

how to model enterprise data for a database.

! Database use and programming

!

how to access and manipulate data.

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Appendix: XAMPP

! XAMPP allows you to treat your computer like a webserver, which is helpful for when you want to developoutside of a live website

! Installing XAMPP gains access to:" Apache" MySQL" PHP" phpMyAdmin" And a few others...

! Be sure to turn on Apache when you use phpmyAdmin

Download and Install

XAMPP! To download XAMPP, select your version from:

" http://www.apachefriends.org/en/xampp.html

! Launch the installer file

" It may be necessary to install XAMPP through Run asAdministrator on Windows

" Unless you know what to exclude, get everything

! Installation will take 15 20 minutes

digital transmission lecture 1

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