Final Review

Sunday March 13th

Databases

– Entities/Rows– Attributes/Columns– Keys– Relationships– Schema– Instance

Databases

– Entities/Rows -”theme”– Attributes/Columns - characterisitics about entities– Keys - unique row identifiers -EVERY ROW MUST

HAVE ONE– Relationships - associations among data -

• Foreign keys

– Schema - Table structure– Instance - Table contents

Good databases

• One copy of data - Why?

• Relationships between tables - How?

Databases operations

• Project

• Select

• Union

• Difference

• Product

Databases operations

• Project - pick columns

• Select - pick rows

• Union - combine two tables

• Difference - remove one table from another

• Product - create all possible pairs

Info Retrieval

• Use QUERIES to retrieve info from databases• Relationships

– One - to - one– One - to - many– Many - to - many

• Primary keys• Foreign keys

Info retrieval

• One - to - many:– The ONE is the primary key and is used as

a foreign key in the MANY’s table

• Many - to - many:– Cross reference table! To reduce into 1 -

to- many

Forms

• GUI• Front end of the database• Easier way to:

– Present info– Add content

• Adding an image to a form– Database stores a link to the image file (same as

html)

Reports

• Make DB look pretty!

• Easier way to:– Arrange data– Present data

• How is it done in access:– Wizard - easier– Design mode - customizable

Binary numbers

• What does each number position represent?

• Convert from hex to decimal

• Convert from binary to decimal

• Why represent info. Using binary numbers?

Representing info in binary

• Text• Color• Pictures• Sound• Anything!

– How are continuous signals represented in binary?

Representing info in binary

• Text• Color• Pictures• Sound• Anything!

– How are continuous signals represented in binary?

FIRST DISCRETIZE (OR DIGITIZE), THEN REPRESENT!

Privacy online

• Privacy Statements

• Cookies– Good?– Bad?– Can I do anything about it?

Privacy principles

• Limited collection– Knowledge and consent whenever appropriate

• Quality– Relevant to the purpose. Accurate and complete

• Purpose– Purpose should be stated. Limit use to purpose

• Use Limitation– Limit the use to the purpose unless authorized

Privacy Principles

• Security– Against disclosure, access, misuse, modification,

destruction, loss

• Openness– Let users know anything you can!

• Participation– Let users have control over their data (as much as

possible

• Accountability– The controller is accountable

First midterm stuff

• HTML

Second midterm stuff