1.3.2 databases

Question 1

what is a relational database?

Answer 1

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

Question 2

what is an entity?

Answer 2

an item of interest about which information is stored

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 identifier for each record in a table

Question 5

what is a foreign key?

Answer 5

the attribute which links two tables together

Question 6

what is a secondary key?

Answer 6

an Index other than the primary key used to search and sort though the database with more convenience and speed

Question 7

what is normalisation?

Answer 7

this is the process of coming up with the best layout for a relational database

Question 8

what does normalisation try to accomplish?

Answer 8

no redundancy, consistent data throughout linked tables, records can be added and removed without issues, complex queries can be carried out

Question 9

what is an index?

Answer 9

an index is a data structure used to look up and access data in database quickly

Question 10

is the primary key automatically indexed?

Answer 10

yes

Question 11

what does capturing data mean?

Answer 11

capturing data is the process of getting the information you wish to use

Question 12

what method do banks use to capture data from cheques?

Answer 12

they use magnetic ink character recognition to get all the details from the amount which must be entered manually

Question 13

what does selecting data mean?

Answer 13

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

Question 14

what does managing the data mean?

Answer 14

managing the data means to manipulate the information in any type of way such as through sorting through it 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

to be in first normal from there must be no attribute that contain more than a single value in a cell

Question 17

what are the requirements to be in second normal form?

Answer 17

the database is in first normal form, there are 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 non key dependencies

Question 19

what does SQL stand for?

Answer 19

structured query language

Question 20

what is SQL?

Answer 20

a declarative language used to manipulate databases

Question 21

what is referential integrity?

Answer 21

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

Question 22

what is a transition defined as?

Answer 22

a transaction is a single operating executed on data

Question 23

what does ACID stand for?

Answer 23

Atomicity, consistency , isolation and durability

Question 24

what does atomicity in ACID mean?

Answer 24

a transition 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 so regardless of the circumstances

Question 28

what is record locking?

Answer 28

record locking is 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