Databases

Question 1

Entity

Answer 1

a category of objects, person or thing of interest of which data needs to be recorded

Question 2

Field

Answer 2

give category headings for each item of data in a database (e.g. Time, Date, Right Ascension, etc.) - also known as attributes

Question 3

Record

Answer 3

a collection of data for one object/person/thing - shown as a single row in a table

Question 4

Table

Answer 4

made up of records and fields and is a collection of related data

Question 5

Primary key

Answer 5

field(s) in a database table that act as a unique identifier for each record

Question 6

Composite primary key

Answer 6

includes two or more attributes to uniquely define a record

Question 7

Foreign key

Answer 7

an attribute that creates a connection between two tables

Question 8

Relational Database Management System (RDBMS)

Answer 8

provides an interface between users and applications and the database

Question 9

Flat file

Answer 9

type of database that stores data in a plain text format

Question 10

Normalisation

Answer 10

process used to create the best possible design for a database

Question 11

First normal form

Answer 11

contains no repeating attributes/group of attributes

Question 12

Second normal form

Answer 12

a table is in 2NF if it’s in 1NF AND contains no partial-key dependencies

Question 13

Third normal form

Answer 13

a table is in 3NF if it’s in 2NF AND contains no non-key dependencies

Question 14

Partial key dependency

Answer 14

occurs when one primary key determines some other attribute(s)

Question 15

Referential integrity

Answer 15

refers to the accuracy and consistency of data within a relationship

Question 16

Client-server database

Answer 16

when a database resides on a server and client applications are written to access the database

Question 17

Record locking

Answer 17

prevents simultaneous access to objects in a database to prevent updates being lost or inconsistencies in the data from occuring

Question 18

Serialisation

Answer 18

technique used to ensure that transactions don’t overlap in time

Question 19

Timestamp ordering

Answer 19

each object in database has a read timestamp and write timestamp - updated whenever an object is read or written

Question 20

Commitment ordering

Answer 20

another serialisation technique that ensures no transactions are lost if two clients are trying to update a record simultaneously