Test 2 Flashcards
Primary Key vs Foreign Key
A primary key is a unique identifier for a record, a foreign key is a key used to link tables and is a field in one table linked to a primary key in another.
Atomicity (When data isn’t atomic and how to make it atomic)
Atomicity –> transaction can happen because data type is correct
Atomicity occurs when the types of data does not share the same data type. for example in a car database a model and make are always different fields
Data integrity – Entity, Domain, Referential
Entity:
Entity integrity is a simple concept that ensures the validity of primary keys
The concept states that each primary key must not be NULL (meaning it must contain a value of some sort)
It also states that each primary key must be unique, meaning no primary key value may be the same as another primary key value in the same record
Domain:
Domain integrity refers to the boundaries that shape the data entered into a database
This can be as simple placing a limit on the length of the data item and enforcing a specific data type
Domain integrity ensures organisation and validity in a database structure
Referential:
Referential integrity states that every foreign key must reference a valid existing value in another table
This means that for every record in a normalised database, the linking element (the foreign key) must exist in another record
Both the primary and foreign keys must be the same data type and length
Interface Design – Strengths and Weaknesses
Navigation
Navigation is logical and easy to follow
Naming of menus is logical
People expect to see particular navigation, show them normal navigation
Provide tabs, menus in predictable places
Provide focus for the most important item on the page/screen
Provide alternative pathways, not just one pathway in and one pathway out
Image navigation icons need to be able to work literally at the slide of a finger. Too small and it won’t work
Text hyperlinks too close together because of small font size can cause navigation problems
Logical Order
A clear and understandable interface is the goal
Order items in the order in which people are going to use them
Put first things up front and in the expected place
Put yourself in the position of the person wanting to use this database, apply order to what they would expect
Inclusivity
Can all people use this software
Does it meet user friendly requirements regardless of
Culture
language
Design it so it has maximum use by the people
If people find it difficult to use, it won’t be used very often.
Design it with the end user in mind. All end users is the focus for inclusivity.
Two legal requirements for software developers creating apps
Two legal requirements for software developers are privacy and misuse of personal information (third party).
Developers must abide. by the Australian. Privacy principles act 1988 which directs business, government. and. others how to use and store personal information.
Difference between a function and formula
Function: A function is a predefined formula that are readily available in a spreadsheet software
Formula: A formula is an expression that is used to calculate the value of a cell.
How can encryption keep data safe?
Passwords:
-type in characters from the keyboard
-more complex passwords are more secure
-long passwords are more secure
Biometrics:
-using part of the body to gain access
-this may replace password access
-eg. finger print access to a device (fingerprint recognition from Wikipedia)
-has two phases. 1. Digitise the information into a database (eg your scanned fingerprint) 2. Access the device with the digitised information (your fingerprint) which matches the version in the database.
-body parts being digitised are scanned by; a finger scanner, hand scanner, face scanner, retina scanner and voice scanner
The purpose of labels in a spreadsheet
To be able to identify the field/attribute.
