INTROFÖRELÄSNING

Question 1

Which level of abstraction is Data, Information and Knowledge?

Answer 1

Data being the lowest(most concrete)

Knowledge being the highest(most abstract)

Question 2

What is unstructured data?

Answer 2

• No storing of individual values, you instead store entire object, graph data, files etc
• Take it as it comes, store it directly in a database
• Easier to store
• Takes up A LOT more space
• Often used for videos, documents, images, webpages etc
• Stores data in its native format

Question 3

What is structured data?

Answer 3

• Managed using SQL
• Predefined format (int, text, date etc.)
• Advantage of being easily entered, stored, queried
• Lives in columns, rows…

Question 4

What is Semi-structured data?

Answer 4

• “Some structure”, some markers/tags that identifies the elements in the data, but without the same rigid structure
• Often stored in markup language type such as XML or JSON

Question 5

List/Spreadsheets are good for?

Answer 5

• Sorting data based on the values in cells(sort by students or course name for example)
• Storing data, add thousands of rows without a problem(Until we run out of RAM)

Question 6

Purpose of Databases?

Answer 6

• Organized collection of data
• And this data can be used to infer information, which is one of its purposes
• Databases also provide organizations structure for data
• Provide mechanism for creating CRUD operations

Question 7

Relational Databases vs Spreadsheets

Answer 7

• No limit on how much data in relational DB, can always add more storage
• Relational DB store information in tables
• Split allows reduction in amount of data redundancy, which is a problem in spreadsheets
• DB allows usage of null/empty values in cells, problematic in Spreadsheets
• More difficult to use DB
• Relational DB reminds itself of Spreadsheets, but might be redundant when working with very small data sets.

Question 8

RDBMS

Answer 8

• Automatically keeps track of relationships between our data
• how it works? Magic

Question 9

3 phases in Database design

Answer 9

Phase 1 - Conceptual design:

• Design phase, focus is on developing conceptual models of data in an organization(conceptualize the relational data models and their attributes as entities)
• Drawing models

Phase 2 - Logical design
* Concretizing our conceptual models into conceptual tables, based on the data used in an organization and previous phase

Phase 3 - Physical design
* Create actual tables in database using SQL

Question 10

3 level design in Layered Architecture

Answer 10

1. Presentation layer
   - Fetching information from user
2. Logic/business layer
   - Take information user inputs, transform it and query dB with the information
   - Handles the response from data layer, then transfers it back to presentation layer
3. Data layer
   - Respond with a response if its validated or not, send it back to logic layer