Appendix C: Databases – Flashcards
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What kind of attribute would be given for a person who does not have an email address?
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Null-valued attribute
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Which of the following is a possible business rule?
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*All of these. A DVD title can have many copies. A customer can purchase many DVDs. DVDs can be purchased by many customers.
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Which of the following is a type of attribute?
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Single-valued attribute *All of these Multi-valued attribute Null-valued attribute
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What is a characteristic of a table?
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Field
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What has only a single value of each attribute of an entity?
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Single-valued attribute
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What kind of attribute is assigned to an attribute when no other value applies or when a value is unknown?
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Null-valued attribute
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What kind of attribute would be age?
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Derived attribute
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What occurs between two entities in which an instance of one entity can be related to only one instance of a related entity?
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One-to-one relationship
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What is a statement that defines an aspect of a business?
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Business rule
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What is a technique for documenting the entities and relationships in a database environment?
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Entity-relationship diagram
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What is a collection of related data elements?
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Record
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Which of the following statements is accurate?
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Each business rule will have entities and sometimes even attributes. A typical business may have hundreds of business rules. *All of these. A correct business rule for one organization may not be correct for another organization.
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What kind of attribute would be date of birth?
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Stored attribute
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What exists to represent the relationship between two other entities?
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Composite entity
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What is composed of rows and columns that represent an entity?
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Table
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What occurs between two entities in which an instance of one entity can be related to many instances of a related entity?
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One-to-many relationship
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What is a foreign key?
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A primary key of one table that appears as an attribute in another table and acts to provide a logical relationship between the two tables
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What occurs when two entities can be related to each other in many instances?
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Many-to-many relationship
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What kind of attribute can be calculated using the value of another attribute?
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Derived attribute
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What is a primary key?
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A field that uniquely identifies a given record in a table
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What expresses the specific number of instances in an entity?
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Cardinality
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What has the potential to contain more than one value for an attribute?
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Multi-valued attribute
