Chapter 8 Flashcards
Data Modeling and Analysis
- Data modeling is a technique for defining business requirements for a database.
Answer: True Page: 270 LOD: Easy
- Data modeling is a technique for organizing and documenting a system’s logical and physical models.
Answer: False Page: 270 LOD: Medium
Rationale: Data modeling is a technique for organizing and documenting a system’s data.
- Data modeling is sometimes called database modeling because a data model is eventually implemented as a database.
Answer: True Page: 270 LOD: Easy
- An identity is a class of persons, places, objects, events, or concepts about which we need to capture and store data.
Answer: False Page: 271 LOD: Medium Rationale: An entity is a class of persons, places, objects, events or concepts about which we need to capture and store data.
- An entity instance is a single occurrence of an entity.
Answer: True Page: 272 LOD: Easy
- An entity existence is a single occurrence of an entity.
Answer: False Page: 272 LOD: Easy
Rationale: An entity instance is a single occurrence of an entity.
- An attribute is a descriptive property or characteristic of an entity.
Answer: True Page: 272 LOD: Easy
- A compound attribute is one that actually consists of other attributes that are logically grouped together.
Answer: True Page: 272 LOD: Easy
- A compound attribute is an attribute that will be expanded into a separate entity.
Answer: False Page: 272 LOD: Medium
Rationale: A compound attribute is one that actually consists of other attributes that are logically grouped together.
- The data type of an attribute defines what type of data can be stored in that attribute.
Answer: True Page: 272 LOD: Easy
- Example data types include: numbers, text, memo, date, time, yes/no, Boolean, value set, or image.
Answer: True Page: 272 LOD: Easy
- A key is an attribute, or group of attributes, that assumes a unique value for each entity instance. It is sometimes called an identifier.
Answer: True Page: 273 LOD: Easy
- A key is an attribute or group of attributes that assumes a unique value for each entity instance. It is sometimes called the domain of the attribute.
Answer: False Page: 273 LOD: Medium
Rationale: A key is an attribute, or group of attributes, that assumes a unique value for each entity instance. It is sometimes called an identifier.
- A concatenated key is a group of attributes that uniquely identifies an instance of an entity.
Answer: True Page: 273 LOD: Easy
- A concatenated key is also known as a composite key or a compound key.
Answer: True Page: 273 LOD: Easy
- A candidate key must be a single attribute.
Answer: False Page: 274 LOD: Medium
Rationale: A candidate key may be a single attribute or a concatenated key.
- A candidate key may be a single attribute or a concatenated key.
Answer: True Page: 274 LOD: Easy
- A primary key is that candidate key that will most commonly be used to uniquely identify a single entity instance.
Answer: True Page: 274 LOD: Easy
- An example of domain would be an attribute called grade where the values could only be A, B, C, D, E, or F.
Answer: True Page: 272 LOD: Medium
- A subsetting criteria is also known as an inversion entry.
Answer: True Page: 274 LOD: Easy
- A subsetting criteria is a domain of attributes whose values are limitless to allow for a variety of subsets to be constructed from a database.
Answer: False Page: 274 LOD: Medium
Rationale: A subsetting criteria is an attribute or concatenated attribute whose finite values divide all entity instances into useful subsets.
- A relationship is a natural business association that exists between one or more entities.
Answer: True Page: 275 LOD: Easy
- A relationship may represent an event that links the entities or merely a physical affinity that exists between the entities.
Answer: False Page: 275 LOD: Hard
Rationale: A relationship may represent an event that links the entities or merely a logical affinity that exists between the entities.
- All data model relationships are unidirectional.
Answer: False Page: 275 LOD: Medium
Rationale: Relationships are bi-directional.
- Because all relationships are bi-directional in an entity relationship diagram, cardinality must be defined in both directions for every relationship.
Answer: True Page: 275 LOD: Easy
- Conceptually cardinality defines the minimum and maximum attributes that can be added to an entity.
Answer: False Page: 275 LOD: Medium
Rationale: Cardinality is the minimum and maximum number of occurrence of one entity that may be related to a single occurrence of the other entity.
- The degree of a relationship is the number of entities that participate in the relationship.
Answer: True Page: 275 LOD: Easy
- A recursive relationship is a relationship with a degree of infinity, because there is no limit to how many entities participate in the relationship.
Answer: False Page: 276 LOD: Medium
Rationale: A recursive relationship is a relationship with a degree of one (1), only one entity participates in the relationship.
- A recursive relationship identifies a relationship that may exist between different instances of the same entity.
Answer: True Page: 276 LOD: Easy
- A ternary relationship is a relationship among three entities.
Answer: True Page: 276 LOD: Easy
- The relationship between a student entity and a curriculum entity would be classified as recursive.
Answer: False Page: 276 LOD: Easy
Rationale: A recursive relationship identifies a relationship that may exist between different instances of the same entity
- During the requirements phase, the physical data model is transformed into the logical data model.
Answer: False Page: 286 LOD: Medium
Rationale: During systems design, the logical data model will be transformed into a physical data model.
- Another name for the logical data model is the database schema.
Answer: False Page: 286 LOD: Medium
Rationale: Another name for the physical data model is the database schema.
- The data model is metadata - that is, it is data about data.
Answer: True Page: 286 LOD: Easy
- The value of a key should not change over the lifetime of each entity instance.
Answer: True Page: 292 LOD: Easy
- Controls must be installed to ensure that the value of a key is valid.
Answer: True Page: 292 LOD: Easy
- An intelligent key is a business code whose structure communicates data about an entity instance (such as its classification, size or other properties).
Answer: True Page: 292 LOD: Easy
- The authors of your textbook recommend the use of intelligent keys since they can be quickly processed by humans without the assistance of a computer.
Answer: True Page: 292 LOD: Medium
- Some experts suggest that you avoid the use of intelligent keys when designing your data model. They argue that because characteristics can change it violates the rule that the value of a key should not change over the lifetime of each entity instance.
Answer: True Page: 292 LOD: Medium
- Serial codes assign sequentially generated numbers to entity instances.
Answer: True Page: 292 LOD: Easy
- Alphabetic codes use finite combinations of letters (and possibly numbers) to describe entity instances.
Answer: True Page: 293 LOD: Easy
- In significant position codes, each digit or group of digits describes a measurable or identifiable characteristic of the entity instance.
Answer: True Page: 293 LOD: Easy