Computing Flashcards

Question

What is a compound key and when is it used?

Answer 1

A compound key combines more than one field in order to make a unique key. In some databases one field is not enough data to uniquely identify a record. In a pack of cards, there are four different suits, hearts, diamonds, spades and clubs. For example, in a pack one single primary key would not be able to identify each different card based on the suit, or on the card value.

Answer 2

A foreign key is a field in a table that is the primary key of another table.

Answer 3

A one-to-one relationship is when there are two tables, both having the same number of rows. One row from table 1 relates directly to one row in table 2. This could be relevant if you have two tables in a database, one for customer names and one for customer details.

Answer 4

In relational databases, a one-to-many relationship occurs when a parent record in one table can potentially reference several child records in another table. The important idea is that the child cannot have more than one parent record. EG | One dentist can have many patients, but many patients can only have one dentist.

Answer 5

The opposite of a one-to-many relationship is a many-to-many relationship, in which a child record can link back to several parent records. EG | Many pupils have many teachers and many teachers have many pupils.

Answer 6

Cascading Style Sheets allow web developers to alter the layout and appearance of their web pages.

Answer 7

The advantages of CSS are: • The layout of many documents or even an entire website can be controlled from one style sheet, reducing the amount of code required for formatting. • The developer gets a more precise control over layout than by using HTML tags. • The developer can apply different layouts to different media types, screen or print etc. • Several different stylesheets can be used to change the look of a site according to users’ preferences

Answer 8

In CSS code there is a selector, a declaration and a value. In the following code, the 'p' is the selector, the color and font-size are the attributes and the 'red' and ' 16px' are the values. The code within the curly brackets ( { } ) is the declaration. After every value, there MUST be a semi-colon as shown below. p { color: red; font-size: 16px; }

Answer 9

• Element selectors: These directly affect an HTML tag of the same name, so they are simply the name of the tag as a piece of text. • ID selectors: These start with a # symbol and will only affect an HTML tag where the ID attribute matches the text following the # symbol. They are normally only used to affect one particular tag, so the ID should be unique to that tag. •Class Selectors: ``` These start with a full-stop (.) and apply to HTML tags where the class attribute matches the text following the full-stop. They are similar to ID selectors, but can apply to multiple HTML sections. ```

Answer 10

The four stages in Rapid Application Development are: 1. Requirements Planning phase 2. User design phase 3. Construction phase 4. Cut over phase

Answer 11

This is similar to the analysis stage but where users, managers and IT staff discuss and agree on what they need, the project scope, its constraints and the system requirements.

Answer 12

During this phase the developers work with users to translate their requirements into prototypes of the different systems required. This is a continuous interactive process that allows users to understand, modify, and eventually approve a working model of the system that meets their needs

Answer 13

This phase is similar to the implementation and testing stages of the waterfall model, but users continue to be involved and can still suggest changes or improvements as the software is built.

Answer 14

In this phase, the software is installed and tested on the new system and user training and maintenance starts.

Answer 15

Rapid Application Development means that the users should be involved at all stages of the development process and that changes to the design can be made at any time throughout the life of the project. It also means that the development process is faster and more flexible.

Answer 16

Addition of products into a 'basket' when shopping. Your name on a website after inputting login details (I.E: "Welcome, Jordan.")

Answer 17

A bank showing you the money in your account or a website automatically logging you out after a period of inactivity.

Answer 18

Parallel processing is when they are two processors working simultaneously to complete tasks.

Answer 19

Because of the size of the processors they would heat up too quickly due to the amount of work they're having to complete. Eventually melting them and causing permanent damage to the processor.

Answer 20

Cache memory is a faster kind of memory which stores copies of data from frequently used main memory locations. The processor will use various techniques to improve performance using the cache including reading ahead in a program to load the cache with instructions which are likely to be needed soon.

Answer 21

Cache memory is a faster kind of memory which stores copies of the data from frequently used main memory locations.

Computing Flashcards

(45 cards)