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Database Design > Quiz 1 > Flashcards

Quiz 1 Flashcards

1
Q
  1. Defined as a concisely written set of users’ requirements, and should be specified in as detailed and complete a form as possible?
A

Data Requirements (91/92)

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2
Q
  1. Requirements that are user operations or transactions that will be applied to the database and may include both retrievals and updates.
A

Functional Requirements (92)* Not specified in ER diagram

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3
Q
  1. This class of design is usually easier to communicate to non-technical users because it doesn’t contain implementation details.
A

Conceptual Design (93)

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4
Q
  1. This class of design is often referred to as the implementation data model.
A

Logical Design (93)

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5
Q

This class of design includes the internal storage structures, file organizations, indexes, and access paths.

A

Physical Design (93)

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6
Q
  1. What are the two types of existence for entities in the Entity Relationship (ER) model (give an example of each type)?
A

a. Physical existence, example: a snowboard (94)
b. Conceptual existence, example: a company (94)

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7
Q
  1. These become a major part of the data stored in the database and describe each entity.
A

Attributes (94/95)

Types: composite vs simple, derived vs store, key vs non-key
Single vs multi-valued
Complex attributes (ie address-phone)

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8
Q
  1. These types of attributes are helpful to model an address when the user needs to refer to each part of the address independently (i.e., state, city, zip code, etc…).
A

Composite Attributes (96) (opposite is atomic)

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9
Q
  1. How do we specify the type of attribute from question 8 on an entity relationship (ER) diagram?
A

Show the composite attribute extending from the entity, then show the simple attributes extending from the composite attribute (114)

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10
Q
  1. With these types of attributes, the value can be determined by one or many other related attributes, or entities.
A

Derived Attributes (97)

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11
Q
  1. How do we specify the type of attribute from question 10 on an entity relationship (ER) diagram?
A

Put the attribute inside of a DASHED OVAL (114)

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12
Q
  1. Give two cases in which we may use the special “NULL” value?
A

If the attribute does not exist (example, apt # for single family home), or if the attribute is uknown (example, unpublished salary for an NFL coach) (97)

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13
Q
  1. These types of attributes have distinct values for each given entity set of an entity type E.
A

Key Attributes (99)
Subclasses: composite key, partial key (weak entity attribute with dotted underline)

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14
Q
  1. How many such entity sets are there for an entity type E with N entity instances (please explain your answer)?
A

There are 2^N entity sets. An entity set is “The collection of all entities of a particular entity type in the database at any point in time” also known as an entity collection (98/99). For each instance, there are two options, is it in the current set or not. For 3 possible instances: is entity 1 included (y/n), is entity 2 included (y/n), and is entity 3 included (y/n) = 2x2x2 = 8.

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15
Q
  1. When an attribute of one entity type refers to another entity type, what generally exists?
A

Relationship (103)

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16
Q
  1. The following is defined as the number of participating entity types in a relationship type R.
A

Degree (104)

17
Q
  1. When the same entity type participates more than once in a relationship type (in different roles), this is referred to as what kind of relationship?
A

Recursive or self-referencing (106)

18
Q
  1. The general term for the combination of cardinality and participation constraints on a relationship type R.
A

Structural Constraints (109)

19
Q
  1. How many possible cardinality ratios are there for binary relationships (list them)?
A

4: 1:1, 1:N, N:1, and M:N (107)

20
Q
  1. This constraint specifies the minimum number of relationship instances that each entity can participate in and is sometimes called the minimum cardinality constraint?
A

Participation Constraint (108)

21
Q
  1. What are the two types participation constraint from (explain what each type means regarding a relationship type R, and two participating entity types E and D)?
A

Total and Partial (108)
For total, the minimum amount is at least 1
for partial, the minimum is 0

22
Q
  1. Regarding attributes on relationship types, which cardinality ratio (of a binary relationship R from question 20) prevents me from migrating to either participating entity type in the relationship type R?
A

M:N because the participating entity type cannot migrate to EITHER. In general the participating entity type cannot migrate to an N side.

23
Q
  1. Entity types that don’t have key attributes of their own are referred to as what?
A

Weak entity type (100)

24
Q
  1. How do we specify weak entity types on an entity relationship (ER) diagram?
A

Double box

25
Q
  1. The type of relationship that relates the weak entity type to its owner entity type?
A

Identifying Relationship (114)

26
Q
  1. How do we specify an identifying relationship on an entity relationship (ER) diagram?
A

Double diamond

27
Q

What is true about the participation of a weak entity type in the relationship type from question 26? What sort of dependency does this indicate?

A

The entity is in total participation (109) *Eludes to existence dependency

28
Q
  1. True or false, entity types in an entity relationship (ER) diagram should be plural?
A

FALSE

29
Q
  1. True or false, attribute names in an entity relationship (ER) diagram should have their first letter capitalized?
A

TRUE

30
Q
  1. This notation allows us to combine both cardinality and participation constraints into one.
A

(min, max) (126)

31
Q
  1. Give an example of this notation where an entity type has total participation.
A

(1,N) or (1,1)

32
Q
  1. The process of defining a set of subclasses of an entity type is referred to as what?
A

Specialization (141)

33
Q

The process of defining a set of superclasses of an entity type is refered to as what?

A

Generalization

34
Q
  1. What are the two constraints we must specify on a subclass / superclass relationship?
A

Disjointness and Completeness

Database Design (4 decks)

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