8.1 Database concepts

Question 1

Database

Answer 1

a structured collection of items of data that can be assessed by different application 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 the table

Question 7

Entity

Answer 7

anything that can have data stored about it

Question 8

Attribute (database)

Answer 8

an individual data item stored for an entity

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, aka 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 if 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 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 contained 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