database management

Question 1

criteria for data integtrity

Answer 1

relevance (provides meaningful info)
accuracy (degree to which data measures against true value)
correctness (conforms to approved standard or agrees with logic)
currency (up to date)
completeness (all required essential data is known)

Question 2

corruption of data

Answer 2

errors in computer data that occur during writing,reading,storage,transmission or processing which introduces unintended changes to og data

Question 3

hard drive failure

Answer 3

failure of hard drive that stores data results in loss of data or data corruption

RAID 1 (mirroring) + RAID 5 (striping) :provides one or more hard drives in case of failure
backup: used to recover prev version of data
audit trails: identify change to data since corruption (if stored in place separate to faulty drive)

Question 4

human error

Answer 4

data accidentally deleted or updated incorrectly

minimise edit privileges: only few trusted,experienced users have edit privileges
audit trail: record changes made, who made it and when
data validation: reject data that does not comply with validation rules

Question 5

power outages

Answer 5

saving data, stopping applications and services process not executed - data loss/corruption

UPS- protects system by providing emergency power when main power source fails
redundant power supply- having multiple power supplies so if one falls second power supply will take over + provide power (hot swappable)

Question 6

malware

Answer 6

corrupted data w viruses,ransomware pr users unintentionally download malware
firewall : prevent malware from entering
anti malware: detect malware + take action
education: educate users on network abt social engineering

Question 7

sql injection

Answer 7

running maliciously intended sql queries to gain access to confidential data or destroy tables

data validation: validate user input to check for possible sql injections
gui components: restrict data input
limit website access to database : remove INSERT,UPDATE,DELETE rights to any website
don’t send db error messages to clients web browser: can be used to understand db structure and adapt their sql injection

Question 8

outdated data

Answer 8

affects currency
add new records
change existing records
deleting records no longer needed

Question 9

invalid data

Answer 9

can be exposed + corrected using validation checks required by scenario w gui components, exception handling and if statements to apply validation rules

Question 10

file synchronisation

Answer 10

done through internet connectivity
having same data on more than 1 device using the same internet credentials

Question 11

SQL

Answer 11

Structured query language
programming language to perform CRUD (create,read,update,delete) operations on a relational database
w data structured into tables linked by primary and foreign keys
relationsl/SQL databases are not flexible, schema (tables) must be designed before data can be added

Question 12

database schema

Answer 12

table design
highly structured and not flexible
column cannot be added or table deleted w/o altering schema
if deleted- may violate referential integrity

Question 13

NoSQL

Answer 13

not only SQL
unstructured, flexible
store data in documents
ideal for storing massive amounts of unstructured data without predefined schema
can adapt to changing data
Document NoSQL db- fileholder that collects data of many diff types
Key-Value NoSQL database uses JSON files with key-value pairs

Question 14

OLTP

Answer 14

OnLine Transactional Processing
type of data processing that quickly processes large volume of simple queries
real time updates -immediately responds to user’s requests

Question 15

data warehouse

Answer 15

combines data from variety of sources w/in an org for the purpose of producing reports and analysis
reports created from complex queries
unlike database, does not contain current info and is not updated in real time
data denormalised

Question 16

OLAP

Answer 16

OnLine Analytical Processing
process data warehouse data - massive volumes of data quickly analysed using OLAP to produce reports
faster than OLTP but queries come out slower

Question 17

big data

Answer 17

massive volume of structured and unstructured data so large that it is difficult to process using traditional database + software techniques
gathered using many sources (eg mobile devices, sensory technologies,sensors,audit trails,pictures,videos,gps signals, transaction records, RFID readers)
used in many areas (eg business, genomics,meteorology, biological and environmental research,complex physics simulations

Question 18

big data charcaterisations

Answer 18

volume: size of data that needs to be analysed and processed. so large- requires different processing techniques- cant be processed by laptop or desktop

velocity- speed at which data is generated. so high- requires distributed processing techniques

variety: variety of sources . data either structured or unstructured

veracity: quality of data, accuracy, applicability . high veracity- many valuable records. low- large proportion of meaningless data

Question 19

KDD
can i see the macros please, kilojules!

Answer 19

knowledge discoverability in databases
process of discovering useful knowledge from, collection of data
data cleaning ( remove inconsistent data)
data integration (combine data from multiple sources)
data selection ( select data relevant to analysis task)
data transformation ( transform data into appropriate form for mining)
data mining ( apply intelligent methods to extract patterns)
pattern evaluation ( interpret patterns of interest )
knowledge presentation ( translate useful patterns into tables/graphs understandable by others)

Question 20

data mining

Answer 20

set of techniques for discovering hidden valid and potentially useful patterns/trends in a data set
attempts to find new relationships amongst data to extract useful info
uses machine learning, statistics, AI, database technology
-extract transform + load data onto data warehouse
-store + manage data in multidimensional db system
-provide data access to business analysts
-analyse data by app software
present data in useful format

Question 21

JSON Files

Answer 21

JavaScript Object Notation
Convenient way of sharing data
Platform independent
More organised than text file
Flexible- can be used in most programming
Data representation format
Commonly used for APIs and configurations

{“Key” : value} - key value pair

Question 22

arrayList

Answer 22

Dynamic- does not store an initial value - grows/shrinks as elements are added/removed

[ //array

{ //each individual object
“Name”: Mr BG , “Age”: 23, “hobbies” : [“weight lifting”,”bowling”]
},
{“Name” : Mr Klaus, “Age” :24, “hobbies”: [“drama”, “singing”]
}
]

Question 23

security measures to ensure data in database is properly protected

Answer 23

keep data up to date with regular edits and purges

refrain from printing out personal info relating to users

Question 24

actions to take in data breach

Answer 24

POPIA requires
- users notified by email or on website that info has been accessed

• authorities notified

Question 25

data persistence

Answer 25

data stored in permanent storage so it’s available again after programme closed and reopened later