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C175 Data Management Foundations > Lesson 4 > Flashcards

Lesson 4 Flashcards

1
Q

binary relationship

A

An ER term for an association (relationship) between two entities.

For example, PROFESSOR teaches CLASS.

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2
Q

cardinality

A
  • A property that assigns a specific value to connectivity
  • expresses the range of allowed entity occurrences associated with a single occurrence of the related entity.
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3
Q

composite attribute

For example, a phone number such as 615-898-2368 may be divided into an area code (615), an exchange number (898), and a four-digit code (2368).

A

An attribute that can be further subdivided to yield additional attributes.

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4
Q

composite identifier

also known as a composite key

A

In ER modeling, a key composed of more than one attribute.

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5
Q

derived attribute

A
  1. An attribute that does not physically exist within the entity and is derived via an algorithm.
  2. For example, the YEARS_EMPLOYED attribute might be derived by subtracting the start date from the current date.
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6
Q

existence-dependent

A
  1. A property of an entity whose existence depends on one or more other entities.
  2. In such an environment, the existence-independent table must be created and loaded first, because the existence-dependent key cannot reference a table that does not yet exist.
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7
Q

existence-independent

A
  • A property of an entity that can exist apart from one or more related entities.
  • Such a table must be created first when referencing an existence-dependent table.
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8
Q

identifiers

A

One or more attributes that uniquely identify each entity instance.

also known as keys

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9
Q

iterative process

A

A process based on repetition of steps and procedures.

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10
Q

mandatory participation

A

A relationship in which one entity occurrence must have a corresponding occurrence in another entity.

  1. For example, an EMPLOYEE works in a DIVISION.
  2. A person cannot be an employee without being assigned to a company’s division.
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11
Q

multivalued attributes

A

An attribute that can have many values for a single entity occurrence.

  1. For example, an EMP_DEGREE attribute might store the string "BBA, MBA, PHD" to indicate three different degrees held.
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12
Q

non-identifying relationship

A

A relationship in which the primary key of the related entity does not contain a primary key component of the parent entity.

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13
Q

optional attribute

A

In ER modeling, an attribute that does not require a value; therefore, it can be left empty.

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14
Q

optional participation

A

In ER modeling, a condition in which one entity occurrence does not require a corresponding entity occurrence in a particular relationship.

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15
Q

participants

A
  • An ER term for entities that participate in a relationship.
  • For example, in the relationship “PROFESSOR teaches CLASS,” the teaches relationship is based on the participants PROFESSOR and CLASS.
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16
Q

recursive relationship

A

A relationship found within a single entity type.

  1. For example, an EMPLOYEE is married to an EMPLOYEE or
  2. A PART is a component of another PART.
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17
Q

relational schema

A

The organization of a relational database as described by the database administrator.

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18
Q

relationship degree

A
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19
Q

required attribute

A

In ER modeling, an attribute that must have a value.

In other words, it cannot be left empty.

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20
Q

simple attribute

A

An attribute that cannot be subdivided into meaningful components.

Compared to composite attribute.

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21
Q

single-valued attribute

A

An attribute that can have only one value.

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22
Q

strong (identifying) relationship

A
  1. This relationship exists whenever the primary key of the related entity contains the primary key components of the parent entity.
  2. A relationship that occurs when two entities are existence-dependent.
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23
Q

strong entity

A
  • An entity that is existence-independent.
  • It can exist apart from all of its related entities.

Also called a regular entity.

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24
Q

ternary relationship

A
  • An ER term used to describe an association (relationship) between three entities.
  • For example, a DOCTOR prescribes a DRUG for a PATIENT.
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25
Q

unary relationship

A
  • An ER term used to describe an association within an entity.
  • For example, an EMPLOYEE might manage another EMPLOYEE.
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26
Q

weak entity

A
  • An entity that displays existence dependence and inherits the primary key of its parent entity.
  • For example, a DEPENDENT requires the existence of an EMPLOYEE.
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27
Q

weak relationship

A

A relationship in which the primary key of the related entity does not contain a primary key component of the parent entity.

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28
Q

Is the entity relationship model (ERM) dependent on the database type?

A

No, the ERM is not dependent on the database type; it serves as a conceptual framework for organizing data regardless of the specific database implementation

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29
Q

Why is The Crow’s Foot notation more implemented than the Chen notation.

A
  1. CF Notation symbols directly translate to database concepts like relationships (one-to-many, etc.)
  2. Offers simplicity visualization of data structures.
  3. This makes it easier to map diagrams to database tables compared to the more abstract Chen notation.
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30
Q

An entity in the entity relationship model corresponds with $ ?

A

Entities in ER models corresponds to a table in the relational environment.

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31
Q

What does a table row represent in the entity relationship model?

A

A table row represents a single entity instance, containing all attributes for that specific occurrence of the entity.

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32
Q

In the Chen and Crow’s Foot notations, an entity is represented with a rectangle containing the entity’s name. (T/F)

A

True

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33
Q

In the original Chen notation how are attributes & attribute names represented?

A
  • Each attribute is represented by an oval
  • The attribute name connected to an entity rectangle with a line.
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34
Q

Why do Software vendors oppose the Chen representation?

A
  • Software vendors may not favor Chen notation because it can be visually complex and use many symbols, potentially making it harder to use and less appealing to a wider audience.
  • This complexity can lead to larger diagrams and a steeper learning curve
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35
Q

What characterizes a composite identifier in database design?

A

A composite identifier is a primary key that consists of more than one attribute used to uniquely identify an entity instance.True

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36
Q

Why is Crow’s Foot notation useless for multi variable attributes?

A
  1. CF notation focuses on relationships between entities.
  2. It uses symbols to represent cardinality and optionality (mandatory or optional) in relationships.
  3. Multi valued attributes are about a single entity.

cardinality (one-to-one, one-to-many, etc.)

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37
Q

How does Composite attributes make it easier to facilitate detailed queries?

A
  1. They group related information together.
  2. Instead of searching through separate fields for each part of an address,you can use the composite “address” attribute to find exactly what you need with a single query.
  3. This makes queries more efficient and easier to formulate.
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38
Q

Do relationships between entities operate in only one direction?

A

No, relationships between entities can operate in both directions, allowing for interactions that can be navigated from either entity involved.

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39
Q

What establishes connectivities and cardinalities in database relationships?

A

Connectivities and cardinalities are established by concise statements known as business rules that define how entities relate to each other.

40
Q

Is there any way to represent cardinality in Chen notation?

A

Chen notation includes methods to represent cardinality through specific symbols that indicate relationships between entities.

41
Q

What does it mean for an entity to have a mandatory primary key in implementation terms?

A
  1. A mandatory primary key means that every record in a database table must have a unique identifier.
  2. This ensures that each entry can be easily distinguished from others, preventing confusion and duplication.
42
Q

Under what conditions does a weak relationship exist in database design?

A

A weak relationship exists if the primary key of the related entity does not contain any primary key components of the parent entity.

43
Q

In a 1:M relationship, what must be done to avoid referential integrity errors?

A

To avoid referential integrity errors in a 1:M relationship, the data of the “1” side must be loaded first, ensuring that reference entities are in place.

44
Q

Are unary relationships common in manufacturing industries?

A

Yes, unary relationships, where an entity relates to itself, are common in manufacturing industries and can represent scenarios such as employee management hierarchies.

45
Q

Are participation & Referential integrity bidirectional in a relationship?

A
  1. Participation relates to whether an entity requires a relationship with another & does not necessarily imply a bidirectional requirement
  2. Referential integrity ensures that such references are valid and do not necessarily imply a bidirectional requirement.
46
Q

When does a weak relationship, also known as a non-identifying relationship, exist?

A

A weak relationship exists if the primary key of the related entity does not incorporate any primary key components from the parent entity, indicating a lack of identity dependency.

47
Q

What does the existence of a mandatory relationship suggest about minimum cardinality?

A

A mandatory relationship indicates that its minimum cardinality must be at least 1 for the mandatory entity, not 0

48
Q

Why must a database designer understand the “1” and “M” sides of each relationship when implementing a small database?

A

Understanding the “1” and “M” sides is crucial for proper relational design, as it determines how entities reference each other and ensures integrity within the database.

49
Q

The _____ notation of entity-relationship modelling can be used for both conceptual and implementation modelling.

A

UML

50
Q

The entity relationship diagram (ERD) represents the _____ database as viewed by the end user.

A

conceptual

51
Q

A(n) _____ is the set of possible values for a given attribute.

A

domain

52
Q

Ideally, an entity identifier is composed of _____ attribute(s)

A

one

53
Q

A _____ attribute can be further subdivided to yield additional attributes.

A

composite

54
Q

A _____ attribute is one that cannot be subdivided.

A

simple

55
Q

The conceptual model can handle _____ relationships and multivalued attributes.

A

M:N

56
Q

A derived attribute is indicated in the Chen notation by a _____ that connects the attribute and an entity.

A

dashed line

57
Q

The __________ attribute need not be physically stored within the database.

A

derived

58
Q

A relationship is an association between _____.

A

Entities

59
Q

_____ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

A

cardinality

60
Q

When the specific cardinalities are not included on the diagram in Crow’s Foot notation, cardinality is implied by the use of _____.

A

symbols

61
Q

Knowing the minimum and maximum number of _____ occurrences is very helpful at the application software level.

A

entity

62
Q

An entity is said to be _____ -dependent if it can exist in the database only when it is associated with another related entity occurrence.

A

existance

63
Q

If an entity can exist apart from all of its related entities, then it is existence-independent, and it is referred to as a(n) _____ entity.

A

strong

64
Q

A weak entity does not have $ attributes to form a $.

A
  1. sufficient
  2. Primary key
65
Q

The existence of a(n) _____ entity indicates that its minimum cardinality is zero.

A

optional

66
Q

The Crow’s foot symbol with two vertical parallel lines indicates _____ cardinality.

A

(1:1)

67
Q

A _____ relationship exists when an association is maintained within a single entity.

A

unary

68
Q

A _____ relationship exists when three entities are associated

A

ternary

69
Q

If an employee within an EMPLOYEE entity has a relationship with itself, that relationship is known as a _____ relationship.

A

recursive

70
Q

To simplify the conceptual design, most higher-order relationships are decomposed into appropriate equivalent _____ relationships whenever possible.

A

binary

71
Q

The entity relationship model uses the associative entity to represent a(n) _____ relationship between two or more entities.

A

M:N

72
Q

When using the Crow’s Foot notation, the associative entity is indicated by _____ relationship lines between the parents and the associative entity.

A

solid

73
Q

______ are charcteristics of entities

A

Attribute

74
Q

A _____ attribute is an attribute that must have a value

A

required

75
Q

______ are underlined in an ER diagram

A

Identifiers

76
Q

A person’s Social Security number would be an example of a ______ ______ attribute.

A

Single valued

77
Q

A ______ attribute need not be physically stored within the database.

A

derived

78
Q

A _____ attribute is an attribute that can be further subdivided to yield additional attributes.

A

composite

79
Q

When indicating cardinality, the first value represents the _____ number of associated entities.

A

minimum

80
Q

The concept of relationship strength is based on how the ______ ______ of a related entity is defined.

A

primary key

81
Q

A ______ relationship is also known as an identifying relationship.

A

strong

82
Q

The Crow’s Foot notation depicts the strong relationship with a(n) _____ line between the entities.

A

solid

83
Q

A weak entity must be ______ dependent.

A

existence

84
Q

The Chen notation identifies a weak entity by using a double-walled entity ________.

A

rectangle

85
Q

Participation is _______ ; if one entity occurrence does not require a corresponding entity occurrence in a particular relationship.

A

optional

86
Q

In Crow’s Foot notation, an optional relationship between entities is shown by drawing a small _____ _____ on the side of the optional entity.

A

small circle/circle (o)

87
Q

________ expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

A

Cardinality

88
Q

A relationship _______ indicates the number of entities or participants associated with a relationship.

A

degree/cardinality

89
Q

‘Is the process of database design considered sequential?

A

No, the process of database design is often iterative, involving repetitions and revisions rather than a strictly linear sequence of steps.

90
Q

The first step in building an entity-relationship diagram (ERD) is _____ .

A

creating a detailed narrative of the organization’s description of operations

91
Q

If Tiny College has some departments that are classified as “research only” and do not offer courses, the COURSE entity of the college database would be _____ the DEPARTMENT entity.

A

optional to

92
Q

An ______ process is based on repetition of processes and procedures.

A

iterative

93
Q

Identifying the attributes of entities helps in the better understanding of ______ among entities.

A

relationships

94
Q

In organizations that generate large number of transactions, _____ are often a top priority in database design.

A

high processing speeds

95
Q

Complex information requirements may $ ?

A
  1. Dictate data transformations OR
  2. Expand the number of entities and attributes within the designs
96
Q

________ not only helps database designers to stay on track during the design process, it also enables them to pick up the design thread when the time comes to modify the design.

A

Documentation

C175 Data Management Foundations (19 decks)

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