The Relational Data Model

Question 1

Relational Data Model

Answer 1

A data model representing data in the form of tables.

Question 2

Relation

Answer 2

A two dimensional table containing rows and columns of data.

Question 3

Recursive Relationship

Answer 3

A relationship that relates an object set to it self.

Question 4

Relation Attribute

Answer 4

A column in a relation

Question 5

Degree of a relation

Answer 5

The number of attributes in a relation

Question 6

Tuple

Answer 6

A row in a relation

Question 7

Attribute Domain

Answer 7

The set from which an attribute takes its values.

Question 8

Null Value

Answer 8

The value given an attribute in a tuple if the attribute is applicable or its value is unknown.

Question 9

Super Key

Answer 9

A set of attributes that uniquely identifies each row in a relation.

Question 10

Key

Answer 10

A minimal set of attributes that uniquely identifies each row in a relation.

Question 11

Functionally Determine

Answer 11

To uniquely determine a value.

Question 12

Composite Key

Answer 12

A key consisting of more than one attribute.

Question 13

Candidate Key

Answer 13

Any set of attributes that could be chosen as a key of a relation.

Question 14

Primary Key

Answer 14

The candidate key designated for principal use in uniquely identifying rows in a relation.

Question 15

Foreign Key

Answer 15

A set of attributes in one relation that constitutes a key in some other or possibly the same relation used to indicate logical links between relations.

Question 16

Recursive Foreign Key

Answer 16

A foreign key that references its own relation.

Question 17

Relational Database Schema

Answer 17

A listing showing relation names attributes and foreign keys

Question 18

Constraint

Answer 18

A rule that restricts the values in a database.

Question 19

Entity Integrity Rule

Answer 19

The value of a non-null foreign key must be an actual key value in some relation.

Question 20

Normalization

Answer 20

The process of converting a relation to a standard form.

Question 21

Data Redundancy

Answer 21

Repetition of data in database.

Question 22

Data Integrity

Answer 22

Consistency of data in a database.

Question 23

Update Anomaly

Answer 23

Data inconsistency resulting from data redundancy and partial update,

Question 24

Deletion Anomaly

Answer 24

Unintended loss of data due to deletion of other data.

Question 25

Insertion Anomaly

Answer 25

In ability to add data to the database due to the absence of other data.

Question 26

Decomposition of Relations

Answer 26

Splitting a relation into multiple relations.

Question 27

Normal Forms

Answer 27

Rules for structuring relations that eliminate anomalies.

Question 28

First Normal Form(1NF)

Answer 28

All attribute values use must be atomic.

Question 29

Atomic Values

Answer 29

Value that is not a set of values or a repeating group.

Question 30

Functional Dependent

Answer 30

The value of an attribute in a tuple determines the value of another attribute in the tuple.

Question 31

Determinant

Answer 31

The attributes on the left side of a functional dependency determine the value of other attributes in the tuple.

Question 32

Second Normal Form(2NF)

Answer 32

No non-key attribute may be function ally dependent on just a part of the key.

Question 33

Projection of A Relation

Answer 33

A relation consisting of selected attributes from another relation.

Question 34

Third Normal Form(3NF)

Answer 34

Every determinant is a key.

Question 35

Boyce-Codd normal form(BCNF)

Answer 35

Every determinant is a key.

Question 36

Transitive Dependency

Answer 36

Occurs when a non-key attribute is functionally dependent on one or more other non-key attributes.

Question 37

Multivalued Dependency (MVD)

Answer 37

A constraint that guarantees the mutual independence of multivalued attributes.

Question 38

Fourth Normal Form(4NF)

Answer 38

A relation that is in third normal form and has no multivalued dependencies.

Question 39

Fifth Normal Form(5NF)

Answer 39

A normal form that eliminates join dependencies.

Question 40

Domain/Key normal form (DKNF)

Answer 40

Requires every constraints to result from definitions of domains and keys.