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Database > Chapter 2 - Slides > Flashcards

Chapter 2 - Slides Flashcards

1
Q

The ____ is very popular because of its

simplicity and mathematical foundation

A

Relational Model

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2
Q

True or False? Relational model shows data to the user in a very simple, logical view as a two-dimensional table.

A

True

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3
Q

What is the strongest characteristic of the Relational Model?

A

the ability to establish relationships among tables, which helps to reduce redundancy

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4
Q

What was the first commercial implementation of the Relational Model?

A

SQL/DS on MVS OS by IBM and the Oracle DBMS in 1980s

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5
Q

What is a model?

A

a simplified version of real-life

complex objects.

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6
Q

What is a data model?

A

a simplified graphical
representation of a database structure and is a
tool to represent the various entity types and
relationships among the entity types.

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7
Q

What does the Entity-Relationship (ER) model provide?

A
  1. An excellent communication tool.

2. A simple graphical representation of data.

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8
Q

The E-R model uses _____ for

graphical representation of the database components

A

E-R diagrams (ERD)

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9
Q

What is an Entity?

A

it is represented by a
rectangle. The name of the entity (set) is written within
the rectangle. Some tools prefer to use uppercase
letters only for entities.

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10
Q

The name of an entity set is a _____

A

single noun

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11
Q

EMPLOYEE, CUSTOMER, and DEPARTMENT are examples of what?

A

Singular entity set names

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12
Q

A ___ represents relationship between the two

entities

A

line

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13
Q

The name of the relationship is an ____ in lowercase letters.

A

active verb

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14
Q

works, manages, and employs are examples of what?

A

relationships

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15
Q

How is 1:1 represented on the ER Model?

A

With 2 vertical lines on each side. (-||——||–) ie. manages

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16
Q

How is 1:M represented on the ER Model?

A

With 1 set of vertical lines on one side and angled lines on the right hand side.
(-||–||-)

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17
Q

How is M:N represented on the ER Model?

A

With 2 angled lines on each side.

(->—

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18
Q

The types of relationships (1:1, 1:M, and M:N) between entities are called:

A

connectivity or

multiplicity

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19
Q

How would you illustrate the following:
An EMPLOYEE supervises a DEPARTMENT, and a
DEPARTMENT has one EMPLOYEE supervisor

A

E -||–(supervises)–||-D

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20
Q

How would you illustrate the following:
A DIVISION contains many FACULTY members, but
a FACULTY works for one DIVISION.

A

D -||–(employs)–

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21
Q

How would you illustrate the following:
An INVOICE contains many ITEMS and an ITEM
can be in more than one INVOICE.

A

INV ->–(contains)–

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22
Q

The relationship between two entities can be given
using the lower and upper limits. This information is
called the ____.

A

cardinality

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23
Q

The ____ is written next to each entity in the

form (n, m)

A

cardinality

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24
Q

a (1, 1) next to
EMPLOYEE means that an employee can supervise a
___ of one and ___ of one department.

A

minimum; maximum

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25
Q

The value (1, N) next to an entity means

A

a minimum of one and a

maximum equal to any number

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26
Q

True or False? Some modern tools do not show cardinality in an E-R diagram.

A

True

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27
Q

True or False? In reality, corporations do not set rules for the minimum and maximum values for cardinality.

A

False, they do.

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28
Q

A corporation may decide that a department must
have a minimum of 10 employees and a maximum of
25 employees, which results in cardinality of:

A

(10,25)

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29
Q

An employee can be part of zero or more than one
department, and an item may not be in any invoice!
These types of decisions are known as ___.

A

business rules

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30
Q

In real life, it is possible to have an entity that is not
related to another entity at all times. The relationship
is known as:

A

an optional relationship.

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31
Q

What is the symbol of an optional relationship?

A

Angled lines with a circle

->o–o

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32
Q

The decomposition from M:N to 1:M involves a third

entity, known as a

A

composite/associative entity

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33
Q

The ____ is created with the primary key
from both tables with M:N relationships. The new
entity has a ___, which is a combination of
primary keys from the original two entities.

A

composite entity; composite key

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34
Q

In a database, there are entities that cannot exist by

themselves. Such entities are known as

A

weak entities

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35
Q

The following example, is an example of what type of entity?

In the employee database, there is an entity called EMPLOYEE with employees’
demographic information and another entity called
DEPENDENT with information about each employee’s
dependents.

A

Weak Entities

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36
Q

The _____ entity cannot exist by itself. In other

words, you need the existence of an employee for his or her dependent to exist in the database.

A

DEPENDENT

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37
Q

Weak entities are symbolically represented as

A

Double-lined rectangles

38
Q

What are Simple attributes?

A

attributes that cannot be subdivided; for

example, last name, city, or gender.

39
Q

What are Composite attributes?

A

attributes that can be subdivided,
into atomic form; for example, a full name can be subdivided
into the last name, first name, and middle initial.

40
Q

What are Single-valued attributes?

A

attributes with a single value; for example, Employee ID, Social Security number, or date of birth.

41
Q

What are Multivalued attributes?

A

attributes with multiple values; for example, degree codes or course registration. The multivalued attributes have to be given special consideration.

42
Q

Every table in the database should have a ___, which uniquely identifies an entity

A

primary key

43
Q

For integrity of data, a ____ should be defined for each table in the database

A

primary key

44
Q

Each table has other columns that do not make up
the primary key for the table, such columns are
called the _____.

A

nonkey columns

45
Q

The nonkey columns
are _____ on the primary key
column

A

functionally dependent

46
Q

What are the three types of Dependency?

A
  1. Total or full dependency
  2. Partial dependency
  3. Transitive dependency
47
Q

What is total dependency?

A

When a nonkey column is
dependent on all primary key columns and shows total
dependency

48
Q

What is Partial dependency?

A

When a nonkey column is dependent on part of the primary key

49
Q

What is Transitive dependency?

A

When a nonkey column is dependent on another nonkey

column

50
Q

When would you need to make a composite key?

A

When no primary key is possible, you need to combine 2 columns with unique data to make a composite.

51
Q

Based on the following column dependencies, would it be partially/transitive/total dependency?

Columns A & B are nonkey columns that are dependent only on a part of the primary key column C.

A

Partially Dependent

52
Q

Based on the following column dependencies, would it be partially/transitive/total dependency?

The nonkey column A is not dependent on
any primary key column but is dependent on another
nonkey column, B.

A

Transitive Dependency

53
Q

Based on the following column dependencies, would it be partially/transitive/total dependency?

The nonkey column A is dependent on both B
and C.

A

Total Dependency

54
Q

The first and foremost step in database creation is
_____, which involves a certain degree of
common sense.

A

database design

55
Q

_______ involves an attempt to

synthesize the database structure to get the “first draft”.

A

Relational database design

56
Q

The initial draft goes through an _____ to

improve the structure

A

analysis phase

57
Q

In the ______, entities and their relationships
are identified. The characteristics or the columns of all entities are also identified, and the designer defines the domains for each column.

A

synthesize phase

58
Q

A process called _____ is a process of analyzing

the tables created by the synthesis process.

A

normalization

59
Q

____ keys will be used to establish relationships

A

Foreign

60
Q

There is a large amount of ____ data in a table

with just eight rows and can pose problems.

A

redundant

61
Q

The redundancy may also lead to ____

A

anomalies

62
Q

A _____ results when the deletion of
information about one entity leads to the deletion of
information about another entity

A

deletion anomaly

63
Q

An ______ occurs when the information
about an entity cannot be inserted unless the
information about another entity is known.

A

insertion anomaly

64
Q

An _____ can occur, if the item price
changes to a new price. The price change is
valid after the change date, but not before the
change date

A

update anomaly

65
Q

Unnecessary and unwanted redundancy and
anomalies are not appropriate in databases.
Such tables are in _____

A

lower normal form

66
Q

______ is a technique to reduce redundancy and  It is a decomposition process to split tables.

A

Normalization

67
Q

The ____ in Normalization is performed carefully so that no

information is lost.

A

splitting

68
Q

The higher the normal form is, the ____ the

redundancy.

A

lower

69
Q

A table is said to be in first normal form, or can be

labeled 1NF, if the following conditions exist:

A
  1. The primary key is defined. This includes a composite
    key if a single column cannot be used as a primary key.
  2. All nonkey columns show functional dependency on the
    primary key components
  3. The table contains no multivalued columns. In a singlevalued column, the intersection of a row and a column returns only one value. In a normalized table, the intersection of a row and a column is a single value.
70
Q

What are some disadvantages of 1NF?

A

A table that is 1NF:

  1. may have redundant data.
  2. does not show data consistency and integrity in the long run
71
Q

A table is said to be in second normal form, or can be labeled 2NF, if the following requirements are satisfied:

A
  1. All 1NF requirements are fulfilled

2. There is no partial dependency

72
Q

____ exists in a table in which
nonkey columns are partially dependent on part
of a composite key

A

Partial dependency

73
Q

Partial dependency only exists in a table with a

_____.

A

composite key

74
Q

If a table is in 1NF and does not have a
composite key, it is in 2NF, because there is
______.

A

no partial dependency

75
Q

A table is said to be in third normal form, or can
be labeled 3NF, if the following requirements
are satisfied:

A
  1. All 2NF requirements are fulfilled

2. There is no transitive dependency

76
Q

A table that has _____ is not
in 3NF, but it needs to be decomposed further
to achieve 3NF

A

transitive dependency

77
Q

A table in 2NF that does not contain any ______ does not need any further decomposition and is automatically in 3NF

A

transitive dependency

78
Q

Other higher normal forms are also possible:

A
  1. Boyce-Codd normal form (BCNF)
  2. Fourth normal form (4NF)
  3. Fifth normal form (5NF)
  4. Domain key normal form (DKNF)
79
Q

A ___ is used to show total
(full), partial, and transitive dependencies in a
table

A

dependency diagram

80
Q

In a dependency diagram:

The _____ components are highlighted. They
are in bold letters and in boxes with a darker
border, and are connected
to each other using a bracket.

A

primary key

81
Q

In a dependency diagram:

The _____ are shown
with arrows drawn above the boxes.

A

total and functional dependencies

82
Q

In a dependency diagram:

The ____ are shown
with arrows at the bottom of the diagram

A

partial and transitive dependencies

83
Q

In the 1NF-to-2NF conversion, all _____ are removed

A

partial dependencies

84
Q

The ____ process splits tables into smaller tables. These tables are joined through common
columns to retrieve information from different tables

A

normalization

85
Q

The more tables you have in a database, the more
___ are needed to get the desired information. In a
multi-user environment, it is a costly overhead, and
system performance is affected

A

joins

86
Q

____ is the reverse process of normalization. It reduces

the normal form, and it increases data redundancy.

A

Denormalization

87
Q

With _____ , the information is stored with
duplicate data, more storage is required, and
anomalies and inconsistent data exist. The designer
has to weigh this against performance to come up with a good design and performance

A

denormalization

88
Q

A table is supposed to describe one ____

A

entity

89
Q

If a table describes multiple entities, it needs to be

_____.

A

decomposed

90
Q

When tables are _____, there should be enough foreign keys to establish relationships among
tables.

A

decomposed

91
Q

_____ should not end up with a table that is not related to any other table in the database.

A

Database design process

Database (6 decks)

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