15%20November

1
15 November

• Review
• Introduction to Databases

2
Take Home Hand In
3
Presentations

• Joseph news
• Cherelle Advertising

4
Grades

• Presentation Primary considerations
• Structure appropriate for presentation
• Class engagement
• Web Page
• Partial credit for fixed pages
• Primary problem links

5
Links

• External links and picture source
• http\\www.
• Tells the browser to go to exactly that place
• Local links (other pages)
• Without http, assumes that its in the same
  folder
• Useful to use when you want to move the pages
• Both different than internal links
• Header on the same page

6
Take Home

• Mozilla WYSIWYG vs. tags
• Programming languages and algebra
• Digital divide or democratizing
• Computers or people adapt

7
Databases

• Backend systems that maintain persistent data
• Behind all commercial web sites
• Tables of information that can be retrieved and
  access other tables
• Keys to access entries directly
• Query languages to retrieve more complex
  information

8
Database Tables vs. HTML Tables

• HTML tables
• Appearance
• Database tables
• Structure separate from data
• No program could definitively retrieve
  information from an HTML table
• What the fields are
• What format are they
• Structural information is called metadata

9
Parts of a database

• A database has a set of tables
• Each table has
• Metadata the structure of the table
• Entities the items in the table
• Each entity has
• Key unique identifier of the entity
• Attributes data about the entity. Also referred
  to as fields
• Table terminology
• Row a single entity and its attributes
• Column a particular field

10
Database example

• Class roll
• PIN is the key. Directly retrieves the
  information about a person
• Other information (attributes) available
• Contact info, gender, semester standing
• Query would allow me to see all freshman women in
  a class

11
Additional abilities

• Can cross tables to retrieve information
• Back to example
• Contact information includes dorm
• Another table about each dorm
• Includes part of campus where it is located
• Can now query for all women freshmen in the class
  that live on south campus

12
Databases vs. Spreadsheets

• Spreadsheet is a simplistic form of a database
• Tends to have more built in operations
• Databases tend to be store and retrieve
• Databases have more complex management
• Guarantees of consistency and durability
• Connections between tables
• Query capability

13
Coming Up

• Wednesday
• Computers in the Arts due
• Topic for final project due