Week 1 Flashcards
What is data?
Data is raw facts; building blocks of information. Also known as unprocessed information.
What is information?
Information is data that has been processed to reveal meaning.
What is a database?
A database (DB) is a managed (specialised and integrated) collection of associated data stored in a computer system, it is:
- Shared by multiple users
- Protected with security measures
- Stored with controlled redundancy
- Can be retrieved quickly
What is a DBMS?
A Database Management System (DBMS) is a program or a collection of programs through which users interact with a database.
What are the roles of the DBMS?
The roles of the DBMS are:
- Intermediary between the user and the database
- Enables data to be shared
- Presents the end user with an integrated view of the data
- Receives and translates application requests into operations required to fulfil the requests
- Hides database’s internal complexity from the application programs and users
What is the importance of DB Design?
A poorly designed DB can:
- generate errors
- lead to bad decisions
- lead to failure of organization
A well-designed DB:
- facilitates data management (e.g. avoid redundant data)
- generates accurate and valuable information
- helps decision making
- leads to business success
What is redundancy?
Redundancy is the duplication of data or the storing of the same data in more than one place.
What are some problems with redundancy?
Some problems with redundancy are:
- Data becomes inaccurate
If a certain field (e.g. address) occurs in the database several times errors will occur if all occurrences of the data are not updated when the field value changes - Extra data entry time
Greater data entry time because the same data has to be entered multiple times. - Extra data storage
This is a minor problem as storage is so cheap these days.
What are the parts of a computer data file?
The parts of a computer data file are:
- File:
Collection of related records - Field:
Group of characters with specific meaning - Record:
Logically connected fields that describe a person, place, or thing - Data:
Raw Facts
What are some problems with file systems for data processing?
Some problems with file systems are:
- Lengthy development times
- Difficulty of getting quick answers
- Complex system administration
- Lack of security and limited data sharing
- Extensive programming
What are the four main problems with file systems for data processing?
The four main problems with file systems for data processing are:
- Structural Dependence
- Data Redundancy
- Data Dependence
- Data Anomalies
What is structural dependence?
Structural dependence is where access to a file depends on its own structure, e.g. the order of the fields. All file system programs are modified to conform to a new file structure
What is data redundancy?
Data redundancy is where different and conflicting versions of the same data appear in different places unnecessarily. This results in data inconsistency and poor data security
What is data dependence?
Data dependence is where changes in the data storage characteristics (the length and data type of fields) affect the application program’s ability to access the data
What are data anomalies?
Data anomalies develop when required changes in redundant data are not made successfully. Anomalies can be created through updates of data, insertion of new data, and deletion of data.
What are the types of database by users?
- Single user DB: Supports only one user at a time
- Multi user DB: Supports multiple users at the same time
- Workgroup DB
Supports a small group of users or a
single department - Enterprise DB
Supports a large group of users or an
entire organisation
- Workgroup DB
What are the types of database by location?
- Centralised DB:
Supports data located at a single site - Distributed DB:
Supports data distributed across several
sites - Cloud DB:
Created and maintained using cloud
data services that provide defined
performance measures for the database
What are the types of database by use?
- Transactional (or Operational) DB:
Supports a company’s day to day
operations - Analytical (Data warehouse) DB:
Stores data used to generate
information required to make tactical or
strategic decisions. Often used to store
historical data. Structure is quite
different.
What are the 5 main parts of a database system?
- Hardware
- Software
- Operating system software
- DBMS software
- Application programs and utility
software - People
- Procedures
- Data
What are the advantages of database systems?
The advantages of a database system include:
- Improved data sharing
- Better data integration and security
- Minimized data inconsistency
- Improved decision making
- Increased end-user productivity
What is data independence?
Data independence is where changes in the structure of the database do not affect the applications functionality.
What is structural independence?
Structural independence is where access to a file does not depend on its own structure. How the data is physically stored will not affect the functionality of the application.
What is data integrity?
Data integrity is ensuring that each row of a table is uniquely identified so that data can be retrieved separately
