1.3: Exchanging data

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Flat-file Database
All the data is stored in a single, two dimensional file.
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Flat-file Database Terms
Rows = records, Columns = fields.
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Relational Database
A relational database uses a DBMS to provide structure, increases data integrity, reduce incompatibility, and remove data dependence.
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Relational Database Terms
Columns = attributes, Rows = tuples, Tables = relations.
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Database Management System (DBMS)
A program to manage databases which allows uses to create, update, read, and delete data.
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Data Manipulation Language (DML)
A system of syntax elements similar to a programming language used for inserting, updating, and deleting data in a database.
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Primary Key
A unique attribute used to identify a tuple (it is customary to underline a primary key).
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Foreign Key
A non-primary attribute in one table which is a primary key in another table and so links the two together.
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Secondary Key
A different attribute that allows the data to be accessed in a different way.
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Entity-relationship Diagram (E-R Diagram)
This is a diagrammatic means of showing a data model/database and illustrates relationships between entities in the database and attributes of each entity.
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Entity
An object, person, event or thing about which data can be recorded.
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Attribute
A property of an entity.
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Relationship
An association between two entities.
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Database Normalisation
A technique for designing databases which aims to minimise data duplication and maximise data integrity.
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Stand Alone
A single computer not connected to any other computers/devices.
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Network
Two or more computers connected to each other.
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Workstation
A computer on a network.
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Server
A computer dedicated to providing a service on a network.
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Node
Refers to any device on a network.
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Local Area Network (LAN)
A network using short-range communications hardware and can be anything from small houses to large offices.
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Wide Area Network (WAN)
A network connecting devices over a large geographical area, e.g. the Internet.
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Metropolitan Area Network (MAN)
A network covering a town or city.
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Personal Area Network (PAN)
A personal network created between two devices (e.g. Bluetooth speaker and mobile phone).
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Transfer Control Protocol (TCP)
This protocol ensures packages are transferred without errors and are reassembled at the receiving end as a TCP header is added.
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Internet Protocol (IP)
This protocol defines how data is transferred across the internet.
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TCP/IP
This protocol provides a real world implementation of the OSI model.
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File Transfer Protocol (FTP)
This protocol defines how files are uploaded and downloaded over the internet.
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Hypertext Transfer Protocol (HTTP)
This protocol transfers webpages.
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Simple Mail Transfer Protocol (SMTP)
This protocol is used for sending e-mail.
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Handshaking
The process of negotiating and agreeing on a protocol.
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Open Systems Interconnection (OSI)
The OSI model is a theoretical framework for defining protocols in 7 layers, where control is passed from one layer to the next.
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User Datagram Protocol (UDP)
A connectionless protocol where one program can send lots of packets to another and that would be the end of the relationship; useful for VOIP and online gaming.
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Domain Name System (DNS)
This is a system for converting domain names (easier to remember) into their equivalent IP address.
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DNS Server
This stores domain names and their corresponding IP address, and if one domain name server does not recognise an IP, it passes the request to another one.
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Packet Switching
Messages are split into equal sized packets with each packet being labelled signifying its destination and order. The packets are sent along communication lines, and each node decides where to send the packets.
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Circuit Switching
Messages are split into packets but a route is reserved before they are sent.
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Network Interface Card (NIC)
This is used on LANs and works at the network layer of the TCP/IP stack which converts data to signals for transfer via a communication medium.
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Unshielded Twisted Pair (UTP)
A cable with a short range which is easy to install but is susceptible to interference.
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Shielded Twisted Pair (STP)
A UTP cable with less interference due to a foil layer, but is more expensive and harder to install.
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Coaxial
A cable with little interference and a large range.
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Fibre Optic
An expensive cable with a large range which cannot be tapped but cannot be bent round corners due to the refraction required for data transmission.
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Repeater
This amplifies the signal when transmitting data over distances further than the medium allows.
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Hub
This takes data transmitted by one node and transmits it to all other channels and is thus considered unintelligent.
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Switch
This takes data transmitted by one node and retransmits it to the channel linking to the receiving node and as such they are intelligent devices and packet sniffing cannot occur.
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Bridge
This provides connections between different networks.
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Router
A way of connecting together LANs and WANs.
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Modem
Stand for modulate-demodulate and provides analogue to digital signal conversion.
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Firewall
Hardware or software which provides internet security by preventing unauthorised access by blocking traffic not coming through open ports.
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Proxy Server
Allow shard access to an internet connection and can also provide additional features such as website filtering and data caching for regularly downloaded content.
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Internet
The world's largest WAN which is a global network connection computers and other devices.
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Client-server Network
A network where one or more servers manage the network, and most nodes are clients which must log on using network credentials to be able to user the network.
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Peer-to-peer Network
A network where no computer has overall control and some computers may provide basic services, e.g. printing, but this is on an ad hoc basis.
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Hypertext Markup Language (HTML)
HTML is a markup language using tags to describe elements of web documents.
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Cascading Style Sheets (CSS)
CSS is a style language that describes the visual presentation of web documents.
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Javascript (JS)
An object orientated computer programming language used to create interactive effects within web browsers.
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Other cards in this set

Card 2

Front

Rows = records, Columns = fields.

Back

Flat-file Database Terms

Card 3

Front

A relational database uses a DBMS to provide structure, increases data integrity, reduce incompatibility, and remove data dependence.

Back

Preview of the back of card 3

Card 4

Front

Columns = attributes, Rows = tuples, Tables = relations.

Back

Preview of the back of card 4

Card 5

Front

A program to manage databases which allows uses to create, update, read, and delete data.

Back

Preview of the back of card 5
View more cards

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