4. Organisation And Structure Of Data Flashcards
Define key field
Unique item of data used to identify the individual record
What is data verification
Used to check data has been copied correctly from original document
What is data validation
Used to check data entered is sensible
Examples of validation checks
☑️ range check
☑️ type check
☑️ length check
☑️ format check
☑️presence check
☑️lookup list
☑️check digit
Examples of verification checks
☑️visual verification
☑️double data entry
What is metadata
Information about the file stored along with it
Metadata examples
Size of image
Image dimensions
Camera used
Image’s exposure
2 common character sets
ASCII
Unicode
Describe ASCII
Contains a limited number of characters but doesn’t use many bits
Describe Unicode
Has more characters than ASCII but uses more memory
Why are character sets used
Files can be sent between computers and understood and decoded
Data type of a record
Can contain multiple data types
Data type of an array
Contains only one data type
Base10/denary numbers 0-16 in Hexadecimal
0-9 = same as base10
10 = A –> 15 = F 16 = 10
Explain the concept of overflow
When bits disappear to the left and right in shift operations & addition, computers have special registers to note these overflows. Bits known as flags are set to remind the computer an overflow has occurred - keeps calculations accurate
Bitmap graphics definition
Made up of pixels. Larger graphics = more pixels needed to maintain quality
What happens when bitmaps are enlarged/scaled up
Quality is lost - known as pixelation
Vector graphics definition
Consist of equations that describe relative distance of a point from a point of origin
Can be enlarged to any size without loss in quality
less storage space
How does sampling sound work
Sample of amplitude at a specific time recorded as a binary number
Greater samples per second (Hz) = ?
Better sound quality
More storage space
Integer
Whole number positive or negative
Boolean
One of two values e.g. True/False, Male/Female
Real
Include rational and irrational numbers - fractions, integers and irrational numbers, positive and negative
Character
a single character “f”
