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88 Cards in this Set
- Front
- Back
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1) A data model is a plan for a database design. |
Answer: TRUE
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2) The method of constructing data models used in the text is the extended entity-relationship (E-R) model.
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Answer: TRUE
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3) An entity is something that users want to track.
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Answer: TRUE
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4) Entities of a given type are grouped into entity classes.
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Answer: TRUE
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5) An entity class is described by the structure of the entities in that class.
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Answer: TRUE
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6) An entity instance is the occurrence of a particular entity.
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Answer: TRUE
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7) An entity instance of an entity class is the representation of a particular entity and is described by the values of the attributes of the entity.
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Answer: TRUE
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8) An identifier of an entity instance is one or more attributes that name or identify entity instances.
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Answer: TRUE
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9) A compound identifier is an identifier consisting of two or more attributes.
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Answer: FALSE
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10) In E-R modeling, an attribute describes the characteristics of an entity.
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Answer: TRUE
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11) In E-R modeling, entities within an entity class may have different attributes.
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Answer: FALSE
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12) An identifier of an entity instance must consist of one and only one attribute.
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Answer: FALSE
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13) A composite identifier is defined as a composite attribute that is an identifier.
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Answer: FALSE
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14) An identifier serves the same role for a table that a key does for an entity.
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Answer: FALSE
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15) Entities can be associated with one another in relationships.
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Answer: TRUE
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16) The degree of a relationship is the number of entity classes in the relationship.
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Answer: TRUE
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17) A binary relationship is a relationship between two or more entities.
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Answer: FALSE
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18) Relationships of degree two are referred to as binary relationships.
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Answer: TRUE
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19) E-R modeling recognizes both relationship classes and relationship instances.
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Answer: TRUE
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20) In today's E-R models, attributes of relationships are still used.
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Answer: FALSE
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21) A single relationship class involves only one entity class.
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Answer: FALSE
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22) A binary relationship is a relationship based on numerical entity instance identifiers.
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Answer: FALSE
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23) The degree of a relationship is expressed as the relationship's maximum cardinality.
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Answer: FALSE
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24) When transforming a data model into a relational design, relationships of all degrees are treated as combinations of binary relationships.
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Answer: TRUE
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25) The principal difference between an entity and a table is that you can express a relationship between entities without using foreign keys.
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Answer: TRUE
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26) When designing a database, first identify the entities, then determine the attributes, and finally create the relationships.
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Answer: FALSE
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27) The notation 1:N shows the relationship's maximum cardinality.
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Answer: TRUE
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28) Relationships are classified by their cardinality.
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Answer: TRUE
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29) A relationship's maximum cardinality indicates the maximum number of entities that can participate in the relationship.
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Answer: FALSE
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30) In an E-R model, the three types of maximum cardinality are 1:1, 1:N and N:M.
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Answer: TRUE
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31) In a 1:N relationship, the term parent refers to the N side of the relationship.
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Answer: FALSE
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32) In a 1:N relationship, the parent entity is on the one side of the relationship, and the child entity is on the many side of the relationship.
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Answer: TRUE
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33) A relationship's minimum cardinality indicates the number of entity instances that must participate in the relationship.
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Answer: TRUE
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34) A relationship's minimum cardinality indicates whether or not an entity must participate in the relationship.
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Answer: TRUE
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35) In an E-R model, the three types of minimum cardinality are mandatory, optional and indeterminate.
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Answer: FALSE
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36) An entity that represents something that can exist on its own is called a strong entity.
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Answer: TRUE
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37) E-R models use an identifying relationship to connect entities that are ID-dependent.
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Answer: TRUE
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38) An ID-dependent entity is an entity whose identifier includes the identifier of another entity.
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Answer: TRUE
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39) ID-dependent entities are associated by a nonidentifying relationship.
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Answer: FALSE
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40) A weak entity is an entity that cannot exist in the database without (and is logically dependent upon) another type of entity also existing in the database.
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Answer: TRUE
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41) ID-dependent entities are a common type of weak entity.
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Answer: TRUE
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42) All weak entities must have a minimum cardinality of 1 on the entity on which it depends.
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Answer: TRUE
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43) Subtype entities contain only attributes unique to the subtypes.
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Answer: TRUE
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44) An attribute that determines which subtype is appropriate is called a discriminator.
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Answer: TRUE
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45) An exclusive subtype pattern has one supertype entity that relates to one or more subtype entities.
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Answer: FALSE
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46) Entities with an IS-A relationship should have the same identifier.
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Answer: TRUE
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47) One example of a database design using an ID-dependent relationship is the association pattern.
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Answer: TRUE
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48) One example of a database design using a strong relationship is the multivalued attribute pattern.
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Answer: FALSE
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49) One example of a database design using an ID-dependent relationship is the archetype/instance pattern.
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Answer: TRUE
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50) Data modelers agree that weak, non-ID-dependent entities exist and are important.
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Answer: FALSE
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51) Entities containing optional sets of attributes are often represented using subtypes.
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Answer: FALSE
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52) The supremetype entity contains the attributes that are common to all subtypes.
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Answer: FALSE
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53) An attribute that determines which subtype is appropriate is called a discriminator.
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Answer: TRUE
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54) Subtypes can be exclusive or inclusive.
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Answer: TRUE
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55) Relationships between supertypes and subtypes are called IS-A relationships.
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Answer: TRUE
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56) Relationships among instances of a single entity class are called redundant relationships.
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Answer: FALSE
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57) There are three types of recursive relationships: 1:1, 1:N and N:M.
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Answer: TRUE
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58) Recursive relationships only exist for one-to-one relationships.
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Answer: FALSE
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59) Which of the following is not a key element of an E-R model?
A) Identifiers B) Entities C) Objects D) Attributes E) Relationships |
Answer: C
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60) Entities of a given type are grouped into an ________.
A) entity class B) entity relationship C) entity instance D) entity attribute E) None of the above. |
Answer: A
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61) The occurrence of a particular entity is called an ________.
A) entity class B) entity relationship C) entity instance D) entity attribute E) None of the above. |
Answer: C
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62) The characteristics of a thing are described by its ________.
A) identifiers B) entities C) objects D) attributes E) relationships |
Answer: D
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63) Attributes may be ________.
A) composite B) element C) multivalued D) A and C E) B and C |
Answer: D
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64) An identifier may be ________.
A) composite B) a single attribute C) a relationship D) A and B E) A, B, and C |
Answer: D
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65) A composite attribute is an attribute that ________.
A) is multivalued B) describes a characteristic of the relationship C) consists of a group of attributes D) is calculated at run-time E) is an identifier |
Answer: C
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66) For a relationship to be considered a binary relationship it must satisfy which of the following conditions?
A) It must involve exactly two entity classes. B) It must have a maximum cardinality of 1:1. C) It must have a maximum cardinality of 1:N. D) A and B E) A and C |
Answer: A
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67) Common variants of the E-R model include:
A) IE Crow's Foot B) IDEF1X C) UML D) A and B E) A, B, and C |
Answer: E
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68) Maximum cardinality refers to ________.
A) the most instances of one entity class that can be involved in a relationship instance with another entity class B) the minimum number of entity classes involved in a relationship C) whether or not an instance of one entity class is required to be related to an instance of another entity class D) whether or not an entity is a weak entity E) None of the above. |
Answer: A
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70) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place many orders and a given order can be placed by at most one customer, which of the following should be indicated in the relationship symbol between the two entities?
A) 0:1 B) 1:1 C) 1:N D) N:1 E) N:M |
Answer: D
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71) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above, and are asked to draw the relationship between them. If a given customer can place many orders and a given order can be placed by one or more customers, which of the following should be indicated in the relationship symbol between the two entities?
A) 0:1 B) 1:1 C) 1:N D) N:1 E) N:M |
Answer: E
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72) Minimum cardinality refers to ________.
A) the most instances of one entity class that can be involved in a relationship with one instance of another entity class B) the minimum number of entity classes involved in a relationship C) whether or not an instance of one entity class is required to be related to an instance of another entity class D) whether or not an entity is a weak entity E) None of the above. |
Answer: C
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73) In a minimum cardinality, minimums are generally stated as ________.
A) 0 B) 1 C) N D) A or B E) A, B, or C |
Answer: D
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74) A hash mark across the relationship line near an entity indicates ________.
A) a maximum cardinality of "zero" B) a maximum cardinality of "one" C) a minimum cardinality of "optional" D) a minimum cardinality of "required" E) None of the above. |
Answer: D
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75) A circle across the relationship line near an entity indicates ________.
A) a maximum cardinality of "zero" B) a maximum cardinality of "one" C) a minimum cardinality of "optional" D) a minimum cardinality of "required" E) None of the above. |
Answer: C
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77) You are given an E-R diagram with two entities, ORDER and CUSTOMER, as shown above. What does the symbol next to the CUSTOMER entity indicate?
A) A maximum cardinality of "zero" B) A maximum cardinality of "one" C) A minimum cardinality of "optional" D) A minimum cardinality of "required" E) None of the above. |
Answer: D
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78) An entity whose identifier includes the identifier of another entity is a(n) ________.
A) strong entity B) weak entity C) ID-dependent entity D) A and C E) B and C |
Answer: E
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79) An entity whose existence depends on the presence of another entity but whose identifier does not include the identifier of the other entity is a(n) ________.
A) strong entity B) weak entity C) ID-dependent entity D) A and C E) B and C |
Answer: B
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80) Which of the following is considered to be a weak entity?
A) ID-dependent entity B) subtype entity C) association entity D) B and C E) A, B, and C |
Answer: E
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81) An entity that holds specialized attributes that distinguish it from one or more other similar entities is a ________.
A) supertype B) subtype C) discriminator D) A and C E) B and C |
Answer: B
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82) Which of the following is not true about subtype entities?
A) Subtypes may be exclusive. B) The supertype and subtypes will have the same identifier. C) Subtypes are used to avoid a situation in which some attributes are required to be null. D) Subtypes have attributes that are required by the supertype. E) Subtypes can produce a closer-fitting data model. |
Answer: E
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83) An attribute that determines which subtype should be used is a ________.
A) supertype B) subtype C) discriminator D) A and C E) B and C |
Answer: C
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84) Discriminators can be ________.
A) exclusive only B) inclusive only C) decisive only D) A or B E) B or C |
Answer: D
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85) Supertype/subtype entities are said to have a(n) ________ relationship.
A) HAS-A B) IS-A C) recursive D) redundant E) multivalue |
Answer: B
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86) To represent an association pattern in an E-R model, ________.
A) create a new ID-dependent entity with a 1:1 relationship to one other entity B) create a new weak, but not ID-dependent entity with a 1:1 relationship to one other entity C) create a new strong entity with a 1:1 relationship to one other entity D) create a new ID-dependent entity with a 1:N relationship to one of two parent entities E) create a new weak, but not ID-dependent entity with a 1:N relationship to one of two parent entities |
Answer: D
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87) To represent a multivalued attribute in an E-R model, ________.
A) create a new ID-dependent entity with a 1:N relationship B) create a new weak, but not ID-dependent entity with a 1:N relationship C) create a new strong entity with a 1:1 relationship D) create a new ID-dependent entity with a 1:1 relationship E) create a new weak, but not ID-dependent entity with a 1:1 relationship |
Answer: A
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88) To represent an archetype/instance pattern in an E-R model, ________.
A) create a new ID-dependent entity with a 1:N relationship B) create a new weak, but not ID-dependent entity with a 1:N relationship C) create a new strong entity with a 1:1 relationship D) create a new ID-dependent entity with a 1:1 relationship E) create a new weak, but not ID-dependent entity with a 1:1 relationship |
Answer: A
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89) When an entity has a relationship to itself, we have a(n) ________.
A) supertype/subtype relationship B) archetype/instance relationship C) recursive relationship D) A or C E) B or C |
Answer: C
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90) Recursive relationships can have which of the following maximum cardinalities?
A) 1:1 B) 1:N C) N:M D) A or B E) A, B, or C |
Answer: E |
