15 November Review Introduction to Databases Take Home

15 November Review Introduction to Databases

Take Home: Hand In

Presentations n n Joseph: news Cherelle: Advertising

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

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

Take Home n n Mozilla: WYSIWYG vs. tags Programming languages and algebra Digital divide or democratizing Computers or people adapt

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

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

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

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

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

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

Coming Up n Wednesday n n Computers in the Arts due Topic for final project due