08.01 - Database Concepts

Question 1

Database

Answer 1

A structured collection of items of data that can be accessed by different applications and programs

Question 2

Relational database

Answer 2

A database where the data items are linked by internal pointers

Question 3

Table

Answer 3

A group of similar data, in a database, with rows for each instance of an entity and columns for each attribute

Question 4

Record (database)

Answer 4

A row in a table in a database

Question 5

Field

Answer 5

A column in a table in a database

Question 6

Tuple

Answer 6

One instance of an entity, which is represented by a row in a table

Question 7

Entity

Answer 7

Anything that can have data stored about it, for example, a person, place, event, thing

Question 8

Attribute (database)

Answer 8

An individual data item stored for an entity, for example, for a person, attributes could include name, address, date of birth

Question 9

Candidate key

Answer 9

An attribute or smallest set of attributes in a table where no tuple has the same value

Question 10

Primary key

Answer 10

A unique identifier for a table. It is a special case of a candidate key

Question 11

Secondary key

Answer 11

A candidate key that is an alternative to the primary key

Question 12

Foreign key

Answer 12

A set of attributes in one table that refer to the primary key in another table

Question 13

Relationship

Answer 13

Situation in which one table in a database has a foreign key that refers to a primary key in another table in the database

Question 14

Referential integrity

Answer 14

Property of a database that does not contain any values of a foreign key that are not matched to the corresponding primary key

Question 15

Index (database)

Answer 15

A data structure built from one or more columns in a database table to speed up searching for data

Question 16

Entity-relationship (E-R) model or E-R diagram

Answer 16

A graphical representation of a database and the relationships between the entities

Question 17

Normalisation (database)

Answer 17

The process of organising data to be stored in a database into two or more tables and relationships between the tables, so that data redundancy is minimised

Question 18

First normal form (1NF)

Answer 18

The status of a relational database in which entities do not contain repeated groups of attributes

Question 19

Second normal form (2NF)

Answer 19

The status of a relational database in which entities are in 1NF and any non-key attributes depend upon the primary key

Question 20

Third normal form (3NF)

Answer 20

The status of a relational database in which entities are in 2NF and all non-key attributes are independent

Question 21

Composite key

Answer 21

A set of attributes that form a primary key to provide a unique identifier for a table