quick revision P1 CS

Data protection act 1998

data must be used fairly and legally, for clear purposes, and collected only for said purposes. Data must be accurate and up-to-date, and people have the right to view data or delete data when requested. Exceptions for this are when there are suspicions of crime or security threat.

Computer misuse act 1990

access to computer which is unauthorised, or accessing computer with intent to facillitate a crime or with unauthorised modification

Copyright, Design, Patents Act 1988

Producer’s rights to their words, such as that work cannot be illegally downloaded, copied, or shared without consent.

Regulation of investigatory powers act 2000

authorities may conduct surveillance on private data and internet data with assistance from ISP.

1NF

no repeating attributes, so must be atomic (one attribute cannot consist of two data items). Cannot be many-to-many as data will repeat.

2NF

1NF and no partial dependencies, so must depend on entirety of composite key and not just part of it (e.g. middle table with both classID and studentID)

3NF

2NF and no non-key dependencies (transitive dependency, where one non-primary attribute can be defined using another non-primary attribute)

SQL order in ascending/descending order

SELECT

FROM

WHERE

ORDER BY … DESC/ … ASC

combine 2 tables

SELECT

FROM

JOIN

ON

WHERE

create table

CREATE TABLE table name

( fieldname1 variable-type NOT NULL PRIMARY KEY,

fieldname2 variable-type,

fieldname3 variable-type)

add column

ALTER TABLE

ADD

remove column

ALTER TABLE

DROP

change data type of column

ALTER TABLE

MODIFY

rename column

ALTER TABLE

RENAME COLUMN … TO …;

create linked table

CREATE TABLE tablename

( fieldname1 type,

fieldname2 type,

fieldname3 type,

FOREIGN KEY key REFERENCES table(key)

FOREIGN KEY key REFERENCES table(key)

PRIMARY KEY (key1, key2)

)

insert data using SQL

INSERT INTO table (field if necessary),

VALUES (attribute1, attribute2…)

update table

UPDATE table

SET attribute = ‘x’,…,

WHERE key = ‘…’

NIC

connects device to network, provides MAC address

Hub vs switch vs router

Hub forwards using a single network, causing a lot of collisions. Switch forwards using MAC address within a single network. Router routes packets using IP address across different networks.

<div> tags

create blocks of HTML content that can be formatted independently using CSS

classes and identifier

#identifier (unique to one element per page), .classes (identifies more than one element per page)

why is Javascript needed

minimises number of files opened, makes code cleaner, can affect multiple HTML code with one line