51. | When mapping a ternary relationship with an associative entity into a relation which of the following is true? |
a. | One relation is created. |
b. | Two relations are created. |
c. | Three relations are created. |
d. | Four relations are created. |
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Answer: (d).Four relations are created.
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52. | When mapping a supertype/subtype relationship which of the following is true? |
a. | The supertype primary key is assigned to each subtype. |
b. | The subtype primary key is assigned to each supertype. |
c. | There is no link between the supertype/subtype entities. |
d. | There is no primary key/foreign key relationship between a supertype/subtype. |
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Answer: (a).The supertype primary key is assigned to each subtype.
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53. | If no multivalued attributes exist in a relation, then the relation is in what normal form? |
a. | First normal form |
b. | Second normal form |
c. | Third normal form |
d. | Fourth normal form |
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Answer: (a).First normal form
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54. | If no multivalued attributes exist and no partial dependencies exist in a relation, then the relation is in what normal form? |
a. | First normal form |
b. | Second normal form |
c. | Third normal form |
d. | Fourth normal form |
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Answer: (b).Second normal form
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55. | A transitive dependency is which of the following? |
a. | A functional dependency between two or more key attributes. |
b. | A functional dependency between two or more nonkey attributes. |
c. | A relation that is in first normal form. |
d. | A relation that is in second normal form. |
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Answer: (b).A functional dependency between two or more nonkey attributes.
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56. | What is the best data type definition for Oracle when a field is alphanumeric and has a fixed length? |
a. | VARCHAR2 |
b. | CHAR |
c. | LONG |
d. | NUMBER |
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Answer: (b).CHAR
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57. | If a denormalization situation exists with a many-to-many or associative binary relationship, which of the following is true? |
a. | All fields are stored in one relation. |
b. | All fields are stored in two relations. |
c. | All fields are stored in three relations. |
d. | All fields are stored in four relations. |
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Answer: (b).All fields are stored in two relations.
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58. | Which of the following is an advantage of partitioning? |
a. | Complexity |
b. | Inconsistent access speed |
c. | Extra space |
d. | Security |
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Answer: (d).Security
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59. | Sequential retrieval on a primary key for sequential file storage has which of the following features? |
a. | Very fast |
b. | Moderately fast |
c. | Slow |
d. | Impractical |
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Answer: (a).Very fast
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60. | A rule of thumb for choosing indexes for a relational database includes which of the following? |
a. | Indexes are more useful on smaller tables. |
b. | Indexes are more useful for columns that do not appear frequently in the WHERE clause in queries. |
c. | Do not specify a unique index for the primary key of each table. |
d. | Be careful indexing attributes that have null values. |
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Answer: (d).Be careful indexing attributes that have null values.
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