Database

Question 1

Database

Answer 1

A structured collection of information that is stored inside a computer system and can easily be accessed, managed, and updated

Question 2

Data concurrency

Answer 2

Instructions happening at the same time

Question 3

Data integrity

Answer 3

Maintains accuracy and consistency of data

Question 4

Database transaction

Answer 4

a series of changes in a database as a single operation

Question 5

Referential integrity

Answer 5

Keeps table links accurate by preventing invalid data

Question 6

1NF

Answer 6

All values are atomic, no repeating groups, no multiple columns for the same data

Question 7

2NF

Answer 7

Already in 1NF, all non-key attributes are fully dependent on the entire primary key

Question 8

3NF

Answer 8

It is in 2NF, all non-key attributes depend on another non-key attribute

Question 9

Normalisation

Answer 9

The process of reorganising data to reduce redundancy

Question 10

Data definition language (DDL)

Answer 10

Used to deifne and a mange the structure of database and objects

Question 11

Database management system (DBMS)

Answer 11

A software that allows users to create, manage, and interact with databases

Question 12

ACID properties A

Answer 12

Atomacity - either all is executed or none

Question 13

ACID properties C

Answer 13

consistency - ensures errors do not create unintended consequences

Question 14

ACID properties I

Answer 14

Isolation - ensures data transactions don’t interfere/ affect others

Question 15

ACID properties D

Answer 15

Durability - ensures changes in the data will be saved

Question 16

Database vs information system

Answer 16

Informations systems are made up of hardware, software, databases… they organise and analyse data. A database is a structured collection of information that is stored inside a computer system and can easily be accessed, managed, and updated

Question 17

Advantages of centrally stored database

Answer 17

Consistent view of the system, centrally updated

Question 18

Relational database management system (RDBMS)

Answer 18

A database management system for databases that are represented / related with logical relations

Question 19

Schema

Answer 19

The logical structure of the data in the entire database

Question 20

Database abstraction levels (3)

Answer 20

Conceptual, logical, physical

Question 21

Physical level

Answer 21

How data is physically stored on hardware. Handles file storage, access paths, efficiency

Question 22

Logical level

Answer 22

The structure of the entire database. Defines tables, relationships, data types, constraints

Question 23

Conceptual level

Answer 23

What users or applications see. Defines user views, hides complexity, controls access

Question 24

Difference between a transaction and operation

Answer 24

An operation is simple and done in one instruction while a transaction is more complex and may consist of multiple operations

Question 25

Capabilities supported by DBMS

Answer 25

Creation, manipulations, and interrogation of database

Question 26

Nature of data dictionary

Answer 26

Describes the data in the database, the meaning, the format, the relationship to other data

Question 27

How to improve response time

Answer 27

Normalise the database to avoid redundancy, write optimised SQL queries, and use specific SELECT statements

Question 28

Methods of database recovery

Answer 28

Backups (copies of the data), rollback (removes all unfinished actions), checkpointing (database writes recent changes to the disk)

Question 29

Primary key

Answer 29

Uniquely identifies each record

Question 30

Foreign key

Answer 30

Primary key in another table used to link them

Question 31

Entity

Answer 31

A thing / object represented in a database

Question 32

Attribute

Answer 32

A characteristic of an entity

Question 33

Validation

Answer 33

Checks if data input makes sense through range check or format check

Question 34

Verification

Answer 34

Check if data was entered correctly like double entries or empty fields

Question 35

Advantages of databases

Answer 35

Reduces data redundancy, ensures data integrity, allows concurrent access

Question 36

Types of update anomaly

Answer 36

Insertion and deletion