Lecture 2: Introduction to Databases

Question 1

Define data

Answer 1

A collection of numbers, images, etc. Data that is given meaning by way of a relational connection (Bob 10 = data —> Bob is 10 years old).

Data is:
- Representation of fact, figure, idea
- Processed by human
- Stored and processed in a compter

Question 2

What is a database?

Answer 2

Electronic file storage where you can input everything you want to store for future reference. The output = the input. A database must be easily accessible

Several definitions:
- Structured collection of records or data that is stored in a computer system
- A persistent repository of data stored in a computer
- A collection of related data
- A tool that stores data and lets you create, read, update, and delete the data in some manner

Question 3

What is a DBMS?

Answer 3

Software designed to store and manage databases

Most DBMSs are used to manage relational databases

Question 4

Why is a DBMS created?

Answer 4

To manage the huge amout of data

Question 5

What does a DBMS provide?

Answer 5

• Data independence and efficient access
• Reduced application development time
• Data integrity and security
• Data administration

Question 6

Examples of DBMS

Answer 6

• Microsoft SQL server (entire management system, not just the database)
• Oracle DB
• PostgreSQL (open source, slower than the rest)
• MySQL (open source, best of all world scenarios, main DBMS in this course)

Question 7

What are essential elements of DBMS

Answer 7

• Implementation of a modelling language: Data model can be represented by data schema. With modeling language, the scheme of each database is defined
• Data structures: Allows DBMS to interact with the data without damaging it
• Data query language
• Transactions: Basis unit of change as seen by the DBMS. Bijv. simultane toegang

Question 8

DB types

Answer 8

• Flat file
• Windows system registry
• Hierarchical DB
• Network DB
• Object database (has the ability to store multimedia)
• Relational DB
• Multidimensional database (Similar to relational database. Cube-like model and easy to maintain)

Question 9

Explain flat file DB

Answer 9

DB just containing text. Simple way to store data

Question 10

Explain Windows system registry

Answer 10

– Hierarchical database
– Hold configuration information for the OS,
applications
– Not for huge amounts of data
– Not for data that changes very frequently

Question 11

Explain hierarchical DB

Answer 11

Not for huge amounts of data. Reconds’ relationships form a tree-like structure. One-to-many relationship (= not flexible)

Question 12

Explain network DB

Answer 12

• Collection of nodes that are connected by links
  
  • Complex relationships
• Many records and accesses them by following
  one of several paths
• Many‐to‐many relationships
• Not common