Data

Question 1

In ASCII, each character is represented with how many bits?

Answer 1

In ASCII, each character is represented with 7 bits

Question 2

What is data validation?

Answer 2

Data validation checks that data being passed into a program meets a set of requirements

Question 3

List the types of validation checks

Answer 3

range check
format check
length check
presence check
check digit

Question 4

What is data verification?

Answer 4

Data verification is used to ensure that the data entered is what the user intended to enter.

Question 5

List the verification methods

Answer 5

Proofreading
Double entry
Parity check
Checksum

Question 6

What kind of errors do check digit algorithms detect?

Answer 6

Check digit algorithms are designed to detect - human transcription errors, such as:
- letter/digit errors, e.g. I -> 1 or O -> 0
- single-digit errors, e.g. 1 -> 2
- transposition errors, such as 12 -> 21

Question 7

advantages of ascii over unicode

Answer 7

ascii consumes less memory

Question 7

advantages of unicode over ascii

Answer 7

1. unicode can represent a large range of characters from special symbols to different languages (more compatible in the globalised world)
2. Flexible Encoding Schemes: multiple encoding forms to ensure efficiency when encoding different languages
3. Backward Compatibility with ASCII, first 128 characters are the same

Question 8

types of erros

Answer 8

1. syntax error
2. runtime error
3. logic error

Question 9

type of contriants to promote data integrity

Answer 9

1. entity integrity: each row of data must have a primary key
2. referential integrity: foreign keg must point to an existing primary key
3. domain integrity: each column should have the same schema
4. user defined integrity: applying further constraints like length

Question 10

purpose of backups

Answer 10

it is to create copies of data to restore it in case of data loss or corruption
backups serve as a safety net to recover data swiftly and minimises downtime in the event of hardware failure, cyber attacks, human errors or natural disasters

it should be
1. created at regular intervals
2. stored offsite
3. tested reguarly

Question 11

purpose of data archivals

Answer 11

(save cost save space)
it involves storing data for long term retention, typically compliance, historical reference
archiving ensured that data remains accessible for as long as needed even if it is not used in active day to day operations

it is stored for long term preservation that can be scaled and is cheap