1.3.2. Databases

Question 1

What is a relational database?

Answer 1

a database that recognises the difference between entities and uses different tables for each entity

Question 2

What is an entity?

Answer 2

an item of interest which information is stored about

Question 3

What is a flat file?

Answer 3

a database that consists of a single file, usually about one entity

Question 4

What is a primary key?

Answer 4

a unique idetifier for each record in a table

Question 5

What is a foreign key?

Answer 5

the attribute which links 2 tables together

Question 6

What is a secondary key?

Answer 6

an index, other than the primary key, used to search and sort through the database with more convenience and speed

Question 7

What is normalisation?

Answer 7

the process of designing the best layout for a relational database

Question 8

What 4 things does normalisation try to accomplish?

Answer 8

1. reduce reduncancy 2. make data consistent throughout linked tables 3. records can be added and removed without issues 4. allows complex queries to be carried out

Question 9

What is an index?

Answer 9

a data structure used to search and access data in a database quickly

Question 10

Is the primary key automatically indexed?

Answer 10

yes

Question 11

What is the defenition of capturing data?

Answer 11

the process of obtaining the information you wish to use

Question 12

What method do banks use to capture data from cheques?

Answer 12

they use MICR to get all of the details apart from the amount which must be entered manually

Question 13

What does selecting data mean?

Answer 13

the process of reducing excess information to obtain only the data you require

Question 14

What does managing the data mean?

Answer 14

manipulating the information in any of way, such as sorting or selecting certain parts using SQL

Question 15

What is the most common language used to manipulate data in databases?

Answer 15

SQL

Question 16

What are the requirements to be in first normal form?

Answer 16

there must be no attribute that contains more than a single value in a cell

Question 17

What are the 2 requirements to be in second normal form?

Answer 17

• the database is in first normal form - there are no partial dependencies (no composite keys)

Question 18

What are the requirements to be in third normal form?

Answer 18

• the database is in second normal form - there are no key dependecies

Question 19

What does SQL stand for?

Answer 19

structured query language

Question 20

What is SQL?

Answer 20

a declaritive language used to manipulate databases

Question 21

What is referential integrity?

Answer 21

the process of ensuring consistency as it makes sure that information is not removed if it is required elsewhere in a linked database

Question 22

What is a transaction defined as?

Answer 22

a single operation executed on data

Question 23

What does ACID stand for?

Answer 23

atomicity consitency isolation durability

Question 24

What does atomicity (in ACID) mean?

Answer 24

a transaction must be processed in its entirety or not at all

Question 25

What does consistency (in ACID) mean?

Answer 25

a transaction must maintain referential integrity rules between linked tables

Question 26

What does isolation in (ACID) mean?

Answer 26

simultaneous execution of transactions should lead to the same result as if they were executed one after the other

Question 27

What does durability (in ACID) mean?

Answer 27

once a transaction has been executed it will remain permanent, regardless of the circumstances

Question 28

What is record locking?

Answer 28

the process of preventing simultaneous access to a record

Question 29

What is the name of an issue that can arise as a result of record locking?

Answer 29

deadlock

Question 30

What is redundancy?

Answer 30

the process of creating more than one copy of data in a physically different location

Question 31

What does MICR stand for?

Answer 31

magnetic ink character recognition