3. Entity-Relationship model

Question 1

database application

Answer 1

a particular database and the associated programs that implement the database queries and updates

Question 2

Entity-Relationship (ER) model

Answer 2

high-level conceptual data model

Question 3

ER diagrams

Answer 3

diagrammatic notation associated with the ER model

Question 4

1. requirements collection and analysis

Answer 4

understand data requirements and specify functional requirements

Question 5

2. conceptual design

Answer 5

Create conceptual schema using high-level conceptual data model

Question 6

2. functional analysis

Answer 6

identify high-level user operations

Question 7

3. logical design / data model mapping

Answer 7

conceptual schema transformed from high-level data model into implementation data model

Question 8

4. Physical design

Answer 8

internal storage structures, indexes, access paths and file organization for database files are specified

Question 9

4. application program design

Answer 9

and implemented as database transactions

Question 10

entity

Answer 10

“thing” in the real world with an independent existence

Question 11

attributes

Answer 11

properties that describe an entity

Question 12

simple vs composite attribute

Answer 12

divisible in smaller subparts or not

Question 13

single-valued vs multivalued attribute

Answer 13

single value or multiple values for one attribute

Question 14

stored vs derived attribute

Answer 14

derivable from another attribute or not

Question 15

null values

Answer 15

when attribute has no value (not applicable or unknown, missing/ unknown)

Question 16

complex attributes

Answer 16

arbitrary nesting by grouping components between parentheses and separating by commas, multivalued between bracets

Question 17

entity type

Answer 17

defines a collection of entities that have the same type

Question 18

entity set

Answer 18

collection of all entities of a particular entity type in the database at any point in time

Question 19

key attribute

Answer 19

attribute whose values are distinct for each individual entity in the set

Question 20

value set (domain)

Answer 20

specified set of values that may be assigned to that attribute for each individual entity

Question 21

relationships

Answer 21

references between entities

Question 22

degree of a relationship type

Answer 22

number of participating entity types (binary if 2, ternary if 3)

Question 23

role name

Answer 23

role that a participating entity from the entity type plays in each relationship instance

Question 24

structural constraints

Answer 24

cardinality ratio and participation constraints

Question 25

cardinality ratio

Answer 25

specifies max number of relationship instances that an entity can participate in

Question 26

participation constraints (minimum cardinality constraint)

Answer 26

specifies whether the existence of an entity depends on its being related to another entity via the relationship type

Question 27

total participation (existence dependency)

Answer 27

every entity in the set of an entity type must be related to a specific entity via a relationship