Lecture 1 - Contextual Database

Question 1

What does a database hold?

Answer 1

All data relevant to our current contextual activity. For example this could be:
- web page links for Web Search
- customer profiles and preferences for a Customer/Retail Store

Question 2

What do we need to be able to do within the database to allow data-driven operation?

Answer 2

Can store humongous data and also update/delete it/ efficiently retrieve

Question 3

What is the fundamental functionality of a DBMS?

Answer 3

Software That Can:
- model data (there exist different models, we will use the relational data one , another example could be Object Oriented)
- access data (query , insert ,update, delete)
- analyze data (visualisation , complex queries)
- store data physcally on a hard disk
- secure data (control access to sensitive & confidential data via e.g. encryption and authentication)
- optimise data access (optimisation algorithms & efficient underlying data structures)
- maintain data consistency (e.g. rollback in case of failure )

Question 4

To a user what is a DBMS? Users’ POV

Answer 4

A box with an interface for users/applications offering the discussed functionality;
- Data Modelling;
- Declarative Programming Language (SQL) to manage & query data

Question 5

What does declarative mean?

Answer 5

We tall what, but not how

Question 6

Example of another declarative language?

Answer 6

HTML

Question 7

What is an example of a Procedural language?

Answer 7

• language which we tell what and how
  e.g. Python, C, Java

Question 8

What does a database have inside?

Answer 8

App connecting to database management system (as we cannot directly interact, there is applications for putting in commands or normal ones that interact using SQL)
Parser
Optimizer
Processing Algorithms
Code Generator

Question 9

What are the 3 families of data?

Answer 9

• Structured (well defined)
• Unstructured (less info on interpretation)
• Semi-structured (e.g. JSON, it is self-descriptive and they interpret themselves)

Question 10

What families of data are managed DBMSs?

Answer 10

All of them: documents, graphs,
multimedia content…

Question 11

What is the datum and metadata of 3 kg in a table?

Answer 11

3 is the datum and kg is the meta-data. Since this would be held in a relation, it is an example of structured data.

Question 12

What is conceptual data modelling?

Answer 12

transform a textual description of a real problem into a set of concepts conveying exactly the same information, but ones that can be well-defined.

Question 13

The 2 approaches for conceptual data modelling?

Answer 13

• Entity-Relationship Modeling
  ( Does not guarantee optimality in operations and query executions.)
• Relational Modeling (gurantees query optimisation)

Question 14

ER Modelling vs Relational Modelling?

Answer 14

E-R model represents the data as entity set, relationship set, and attributes.It is a conceptual model.

The relational Model describes data in a table as attributes and tuples or records.This model is the logical representation of the data model. Better for implementation!

Question 15

What do both models have (contextually)?

Answer 15

entities
attributes
relationships