Quiz 1

Question 1

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

Answer 1

Data Requirements (91/92)

Question 2

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

Answer 2

Functional Requirements (92)* Not specified in ER diagram

Question 3

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

Answer 3

Conceptual Design (93)

Question 4

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

Answer 4

Logical Design (93)

Question 5

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

Answer 5

Physical Design (93)

Question 6

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

Answer 6

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

Question 7

6. These become a major part of the data stored in the database and describe each entity.

Answer 7

Attributes (94/95)

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

Question 8

7. 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…).

Answer 8

Composite Attributes (96) (opposite is atomic)

Question 9

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

Answer 9

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

Question 10

9. With these types of attributes, the value can be determined by one or many other related attributes, or entities.

Answer 10

Derived Attributes (97)

Question 11

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

Answer 11

Put the attribute inside of a DASHED OVAL (114)

Question 12

11. Give two cases in which we may use the special “NULL” value?

Answer 12

If the attribute does not exist (example, apt # for single family home), or if the attribute is uknown (example, unpublished salary for an NFL coach) (97)

Question 13

12. These types of attributes have distinct values for each given entity set of an entity type E.

Answer 13

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

Question 14

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

Answer 14

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.

Question 15

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

Answer 15

Relationship (103)

Question 16

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

Answer 16

Degree (104)

Question 17

17. 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?

Answer 17

Recursive or self-referencing (106)

Question 18

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

Answer 18

Structural Constraints (109)

Question 19

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

Answer 19

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

Question 20

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

Answer 20

Participation Constraint (108)

Question 21

21. 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)?

Answer 21

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

Question 22

22. 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?

Answer 22

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

Question 23

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

Answer 23

Weak entity type (100)

Question 24

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

Answer 24

Double box

Question 25

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

Answer 25

Identifying Relationship (114)

Question 26

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

Answer 26

Double diamond

Question 27

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?

Answer 27

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

Question 28

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

Answer 28

FALSE

Question 29

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

Answer 29

TRUE

Question 30

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

Answer 30

(min, max) (126)

Question 31

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

Answer 31

(1,N) or (1,1)

Question 32

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

Answer 32

Specialization (141)

Question 33

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

Answer 33

Generalization

Question 34

33. What are the two constraints we must specify on a subclass / superclass relationship?

Answer 34

Disjointness and Completeness