Entity-Relationship Modeling and Subtypes - Quiz

1. C 2. B 3. A 4. C 5. B 6. A 7. D 8. C 9. D 10. A 11. A 12. C 13. B 14. A 15. C 16. D 17. D 18. B 19. C 20. C 21. B 22. A 23. D 24. B 25. D 26. A 27. D 28. A 29. C 30. B 31. A 32. B 33. C 34. B 35. D 36. B 37. D 38. B 39. A 40. A 41. B 42. A 43. D 44. A 45. B 46. D 47. B 48. FALSE 49. TRUE 50. TRUE 51. FALSE 52. FALSE 53. TRUE 54. FALSE 55. TRUE 56. FALSE 57. FALSE 58. FALSE 59. FALSE 60. TRUE 61. FALSE 62. FALSE 63. TRUE 64. TRUE 65. FALSE 66. FALSE 67. TRUE 68. TRUE 69. TRUE 70. TRUE 71. FALSE 72. TRUE 73. TRUE 74. TRUE 75. TRUE 76. FALSE 77. TRUE 78. FALSE 79. TRUE 80. FALSE 81. TRUE 82. FALSE 83. TRUE 84. FALSE 85. TRUE 86. FALSE 87. TRUE 88. TRUE 89. The business environment has drastically changed since the relational model was first introduced in the 1970s. Business relationships are more complex, and organizations must have ways to represent data to represent the complexity. Organizations must be prepared to segment their markets as well as customize their products. The enhanced E-R model has evolved to represent these changes and also is similar to the object -oriented data model. 90. A subtype is an entity which represents data meaningful to the organization. For example, an undergraduate student and a graduate student might be a subtype. A supertype is a generalization of various subtypes and contains attributes which are common to both. Supertypes and subtypes may have relationships with other entities. Also, a subtype inherits the attributes of its supertype. 91. Generalization is the process of defining a more general entity type from a set of more specialized entity types. For example, if we had undergraduate and graduate students with similar attributes , then we might create a student supertype. The student supertype would then contain the attributes that all subtypes have in common. Specialization, on the other hand, would occur when we discover that we have a student type but there are different attributes for different types of students. In this case, we would create subtypes which would contain unique attributes for that subtype. 92. It is best to use a supertype/subtype hierarchy when there are attributes that apply to some but not all instances of an entity type. For example, if we have an employee entity type and there is an hourly wage attribute that only applies to hourly employees, it may be best to use a supertype/subtype relationship. Another reason for using supertype/subtype relationships is when you have instances of a subtype that participate in a relationship unique to that subtype. For example, if we have a contractor subtype of employee that has a relationship with staffing agency, then it would be best to use supertype/subtype relationship. 93. Total specialization would be used when you know that there are no other subtypes of a supertype other than those defined. For example, if we only had undergraduate and graduate students but no other types of students, then we would use total specialization. However, if there were students other than graduate and undergraduate, such as just a general student, then we would want to use partial specialization. 94. The disjoint rule is used when you wish to specify that an entity instance can only be one type of subtype. For example, if a student could only be a graduate or undergraduate student, but not both. The overlap rule specifies that an entity instance could be one or more subtypes. For example, if an instance of a person supertype could be a faculty member as well as a student subtype, then we would use the overlap rule. 95. When we have overlapping subtypes, we need to create a composite subtype discriminator with Boolean values. 96. Attributes are assigned at the highest logical level that is possible in the hierarchy. For example, in the following diagram one would assign the name to the person supertype so that it could be shared by as many subtypes as possible. 97. Subtypes that are lower in the hierarchy inherit attributes not from their immediate supertype but also from all supertypes higher in the hierarchy all the way to the root. 98. An entity cluster is a group of entities and relationships which act as one entity. Entity clustering can be thought of as a way to decompose a data model hierarchically, gaining finer and finer views. Entity clusters can interact with other entity clusters just like entities can interact with each other. 99. Most organizations can no longer afford to have data models developed in house, both in terms of labor costs as well as time. As such, the role of data modeler is evolving from artisan to that of engineer. A packaged data model allows one to customize an organization's database needs using a superset of the model needed by the organization. 100. A packaged data model is quite extensive, so you would begin with the part of the data model which you will use for your situation. You would start first with entities, then attributes and then relationships. The next step is to rename the data elements to terms that are meaningful to your organization. Since the packaged data model may be used to replace an existing system, the next step is to map the packaged model to the current database. This mapping will be used later for data migration. Perhaps the most challenging step is to determine the business rules for the new system. 1. Which of the following is a generic entity type that has a relationship with one or more subtypes? A) Megatype B) Subgroup C) Supertype D) Class 2. Given the following entities, which of the choices below would be the most complicated? Automobile: VIN, EngineSize,NumberOfDoors, NumberOfPassengers,, FuelType, Transmission SUV: VIN, EngineSize, NumberOfPassengers, NoWheelDrive, FuelType, Transmission Truck: VIN, EngineSize, NoWheelDrive, FuelType, Transmission, Payload A) Keep only the Truck entity type. B) Define one vehicle entity type to hold all entities. C) Define a supertype called vehicle and make each of the entities subtypes. D) Define a separate entity type for each entity. 3. The property by which subtype entities possess the values of all attributes of a supertype is called: A) attribute inheritance. B) hierarchy reception. C) generalization. D) class management. 4. Subtypes should be used when: A) supertypes relate to objects outside the business. B) the instances of a subtype do not participate in a relationship that is unique to that subtype. C) there are attributes that apply to some but not all instances of an entity type. D) none of the above. 5. In the figure below, which of the following are subtypes of patient? A) Physician B) Outpatient C) Bed D) All of the above 6. The process of defining one or more subtypes of a supertype and forming relationships is called: A) specialization. B) selecting classes. C) creating discord. D) generalization. 7. In the figure below, to which of the following entities are the entities "CAR" and "TRUCK" generalized? A) Make B) Price C) Model D) Vehicle 8. The process of defining a more general entity type from a set of more specialized entity types is called: A) specialization. B) normalization. C) generalization. D) none of the above. 9. Which of the following is a completeness constraint? A) Total recall B) Partial generalization C) Partial hybridization D) Total specialization 10. The following figure is an example of: A) total specialization. B) completeness. C) partial specialization. D) disjointness. 11. The ________ rule specifies that an entity instance of a supertype is allowed not to belong to any subtype. A) partial specialization B) total specialization C) disjointedness D) semi-specialization 12. The following figure is an example of: A) total specialization. B) disjoint completeness. C) partial specialization. D) transunion constraint. 13. The ________ rule specifies that each entity instance of the supertype must be a member of some subtype in the relationship. A) partial specialization B) total specialization C) total convergence D) semi-specialization 14. A ________ constraint is a type of constraint that addresses whether an instance of a supertype must also be an instance of at least one subtype. A) completeness B) disjoint C) overlap D) weak 15. In the figure below, a student: A) must be a graduate student or an undergraduate student. B) must be at least a special student. C) must be a graduate student, an undergraduate, a special student or some other type of student. D) none of the above. 16. The ________ rule specifies that an entity can be a member of only one subtype at a time. A) exclusion B) inclusion C) removal D) disjoint 17. A ________ addresses whether an instance of a supertype may simultaneously be a member of two or more subtypes. A) total specialization B) partial specialization C) disjoint rule D) disjointedness constraint : 18. In the figure below, the patient must be either an outpatient or a resident patient.This is an example of the ________ rule. A) overlap B) disjoint C) generalization D) specialization 19. Which of the following statements is true about the figure shown below? A) A rental unit must be either an apartment or a house and could be both. B) A rental unit must be either an apartment or a house and cannot be both at the same time. C) A rental unit can be either an apartment, house or just a rental unit; it may not be more than one at the same time. D) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartment and a house at the same time. 20. Which of the following statements is true about the figure shown below? A) A rental unit must be either an apartment or a house and could be both. B) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartment and a house at the same time. C) A rental unit must be either an apartment or a house and cannot be both at the same time. D) A rental unit can be either an apartment, house or just a rental unit; it may not be more than one at the same time. 21. Which of the following statements is true about the figure shown below? A) A rental unit must be either an apartment or a house and cannot be both at the same time. B) A rental unit must be either an apartment or a house and could be both. C) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartment and a house at the same time. D) A rental unit can be either an apartment, house or just a rental unit; it may not be more than one at the same time. 22. Which of the following statements is true about the figure shown below? A) A rental unit can be an apartment, a house or just a rental unit. It could be both an apartment and a house at the same time. B) A rental unit must be either an apartment or a house and could be both. C) A rental unit can be either an apartment, house or just a rental unit; it may not be more than one at the same time. D) A rental unit must be either an apartment or a house and cannot be both at the same time. 23. An attribute of the supertype that determines the target subtype(s) is called the: A) subtype decision. B) disjoint indicator. C) determinant. D) none of the above. 24. The ________ rule states that an entity instance can simultaneously be a member of two (or more) subtypes. A) total specialization B) overlap C) partial specialization D) disjoint 25. The following diagram shows: A) the overlap rule. B) total specialization. C) partial specialization. D) none of the above. 26. The subtype discriminator in the figure below is: A) Part_Type. B) Location. C) Manufactured Part. D) Part_No. 27. The subtype discriminator is a composite attribute when there is a(n): A) partial specialization. B) disjoint rule. C) full specialization. D) overlap rule. 28. The following figure shows an example of: A) the overlap rule. B) the completeness rule. C) the disjoint rule. D) the underdog rule. 29. In a supertype/subtype hierarchy, each subtype has: A) at most two supertypes. B) many supertypes. C) only one supertype. D) at least one subtype. 30. In a supertype/subtype hierarchy, subtypes that are lower in the hierarchy inherit attributes from not only their immediate supertype but from all ________ in the hierarchy. A) subtypes B) supertypes C) dimensions D) constraints 31. The following figure shows a(n): A) supertype/subtype hierarchy. B) completeness constraint. C) disjoint constraint. D) spindle constraint. 32. Which statement is true about the following diagram? A) All attributes of graduate are inherited by person. B) All attributes of person and student are inherited by undergraduate. C) A person can only be a faculty, student or staff. D) A student can be both an undergraduate and a graduate student at the same time. 33. An entity cluster is: A) a useful way to present data for a small and fairly simple organization. B) a way of developing more granular views of the data model. C) a set of one or more entity types and associated relationships grouped into a single abstract entity type. D) a formal method for specifying attributes of related entities. 34. The figure below is an example of a(n): A) supertype/subtype hierarchy. B) entity cluster. C) hierarchical data model. D) none of the above. 35. An entity cluster can be formed by: A) combining directly related entity types and their relationships. B) abstracting a supertype and its subtype. C) combining a strong entity and its weak entities. D) all of the above. 36. Packaged data models: A) are ready to use right out of the box. B) require customization. C) cannot be used for most applications. D) allow partial specialization. 37. Which of the following is NOT true of packaged data models? A) Relationships are connected to the highest -level entity type in an order that makes sense. B) All subtype/supertype relationships follow the total specialization and disjoint rules. C) No entities on the many side of a relationship can be weak. D) Both B and C. 38. A generic or template data model that can be reused as a starting point for a data modeling project is called a(n): A) enterprise data model. B) universal data model. C) packaged data model. D) none of the above. 39. Using a packaged data model, projects take less time and cost because: A) essential components and structures are already defined. B) less personnel are required. C) there is more time taken to model the enterprise. D) none of the above. 40. All of the following are advantages of packaged data models EXCEPT: A) more one-to-one relationships give the data model more flexibility. B) projects take less time and cost less. C) packaged data models can be built using proven components evolved from cumulative experiences. D) the data model is easier to evolve. 41. All of the following are steps to using a packaged data model EXCEPT: A) rename the identified data elements. B) utilize all business rules that come with the packaged data model. C) map data to be used in packages with existing data in the current databases. D) identify the parts of the data model that apply to your data modeling situation. 42. When identifying with the parts of the packaged data model that apply to your organization, you should first start with: A) entities. B) relationships. C) primary keys. D) attributes. 43. The third step in the data modeling process with a packaged data model is: A) rename identified data elements. B) rename relationships. C) interview users. D) map data to be used from package to data in current databases. 44. A good method for identifying inconsistencies and finding hidden meaning in the customized purchased data model is: A) data profiling. B) data analysis. C) user interviews. D) data volume usage analysis. 45. The most important challenge of customizing a purchased data model is: A) getting user buy-in. B) determining the business rules that will be established through the data model. C) user training. D) implementation. 46. In packaged data models, strong entities always have ________ between them. A) 1:M relationships B) weak entities C) 1:1 relationships D) M:N relationships 47. In packaged data models, all subtype/supertype relationships follow the ________ and ________ rules. A) partial specialization and disjoint B) total specialization and overlap C) total specialization and disjoint D) partial specialization and overlap 48. A subtype is a generic entity that has a relationship with one or more entities at a lower level. 49. One of the major challenges in data modeling is to recognize and clearly represent entities that are almost the same. 50. An entity instance of a subtype represents the same entity instance of the supertype. 51. A member of a subtype does NOT necessarily have to be a member of the supertype. 52. Supertype/subtype relationships should be used when the instances of a subtype participate in no relationships which are unique to that subtype. 53. Specialization is the reverse of generalization. 54. Generalization is a top -down process. 55. A completeness constraint may specify that each entity of the supertype must be a member of some subtype in the relationship. 56. The total specialization rule states that an entity instance of a supertype is allowed not to belong to any subtype. 57. The following figure is an example of total specialization. 58. When the total specialization rule is set for a supertype/subtype relationship, one could roughly compare the supertype to an abstract class in object -oriented programming. 59. The disjoint rule specifies that if an entity instance of the supertype is a member of one subtype, it MUST simultaneously be a member of another subtype. 60. The overlap rule specifies that if an entity instance of the supertype is a member of one subtype, it can simultaneously be a member of two (or more) subtypes. 61. The following figure is an example of the overlap rule. 62. In the figure shown below, a rental unit can be both a house and an apartment. 63. In the figure shown below, a rental unit has to be either a house or an apartment. 64. In the figure shown below, there could be an instance of a rental unit that is neither an apartment nor a house. 65. In the figure shown below,a rental unit can be both an apartment and a house but must be at least one. 66. When subtypes are overlapping, an additional field must be added to the supertype to act as a discriminator. 67. There are three separate discriminators in the following diagram because of the overlap rule. 68. A subtype can become a supertype if the subtype has other subtypes beneath it. 69. The following diagram is an example of a supertype/subtype hierarchy. 70. In a supertype/subtype hierarchy, attributes are assigned at the highest logical level that is possible in the hierarchy. 71. Subtypes at the lowest level of a hierarchy do not inherit attributes from their ancestors. 72. Entity clustering is a methodology for grouping one or more entity types and associated relationships into a single abstract entity type. 73. An entity cluster should focus on some area of interest to some community of users, developers or managers. 74. An entity cluster can have a relationship with another entity cluster much the same way that an entity can have a relationship with another entity. 75. Packaged data models are meant to be customized. 76. Packaged data models use an entity type to store union data. 77. A universal data model is a generic or template data model that can be reused as a starting point for a data modeling project. 78. Packaged data models cause projects to take more time to build. 79. Packaged data models can be developed using proven components. 80. Data models of an existing database are harder for data modelers to read. 81. Packaged data models are as flexible as possible because all supertype/subtype relationships allow the total specialization and overlap rules. 82. Creating a data model from a packaged data model requires much more skill than creating one from scratch. 83. It is easier t o share information across organizations if companies in the same industry use the same universal data model as the basis for their organizational databases. 84. Adapting a packaged data model from your DBMS vendor makes it difficult for the application to work with other applications from the same vendor. 85. Because a purchased data model is extensive, you begin by identifying the parts of the data model that apply to your data modeling situation. 86. You will never need to map data in current databases to data in a packaged data model. 87. Mapping existing data to new data in a packaged data model is useful for developing migration plans. 88. It is easy to miss the opportunity to visualize future requirements shown in the full data model when using a packaged data model. 89. Explain why the E-R model needed to be expanded into the enhanced E -R model. 90. Explain the terms subtype and supertype. Discuss the differences between them. 91. Compare and contrast generalization and specialization. 92. Discuss the reasoning behind using supertype/subtype relationships. 93. Discuss when you would use total specialization and when you would use partial specialization. 94. Contrast the overlap rule to the disjoint rule. 95. Describe how subtype discriminators are used when we have overlapping subtypes. 96. Discuss how attributes are assigned in a supertype/subtype hierarchy. 97. Discuss how attribute inheritance works in a supertype/subtype hierarchy. 98. Explain what entity clustering is. 99. Why are packaged data models gaining popularity? 100. How is the data modeling process different when starting with a purchased solution?