Lecture 2: Introduction to Databases Flashcards
Define data
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
What is a database?
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
What is a DBMS?
Software designed to store and manage databases
Most DBMSs are used to manage relational databases
Why is a DBMS created?
To manage the huge amout of data
What does a DBMS provide?
- Data independence and efficient access
- Reduced application development time
- Data integrity and security
- Data administration
Examples of DBMS
- 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)
What are essential elements of DBMS
- 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
DB types
- 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)
Explain flat file DB
DB just containing text. Simple way to store data
Explain Windows system registry
– Hierarchical database
– Hold configuration information for the OS,
applications
– Not for huge amounts of data
– Not for data that changes very frequently
Explain hierarchical DB
Not for huge amounts of data. Reconds’ relationships form a tree-like structure. One-to-many relationship (= not flexible)
Explain network DB
- 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