Frage 1
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The entity integrity rule requires that ____.
Antworten
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all primary key entries are unique
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a part of the key may be null
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foreign key values do not reference primary key values
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duplicate object values are allowed
Frage 2
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The referential integrity rule requires that ____.
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every null foreign key value must reference an existing primary key value
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an attribute have a corresponding value
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every non-null foreign key value reference an existing primary key value
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you delete a row in one table whose primary key does not have a matching foreign key value in another table
Frage 3
Frage
The ____ depicts the arrangement of higher-level entity supertypes (parent entities) and lower-level entity subtypes (child entities).
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subtype discriminator
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inheritance
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specialization hierarchy
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entity supertype
Frage 4
Frage
Every subtype can have ____ supertype to which it is directly related.
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none
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only one
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one or many
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many
Frage 5
Frage
Every subtype can have ____ supertype to which it is directly related.
Antworten
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none
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only one
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one or many
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many
Frage 6
Frage
A specialization hierarchy can have ____ levels of supertype/subtype relationships.
Antworten
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none
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only one
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one or many
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many
Frage 7
Frage
The property of ____ enables an entity subtype to inherit the attributes and relationships of the supertype.
Antworten
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subtype discriminator
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inheritance
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specialization hierarchy
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entity supertype
Frage 8
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One important inheritance characteristic is that all entity subtypes inherit their ____ attribute from their supertype.
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primary key
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natural key
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foreign key
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surrogate key
Frage 9
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What feature is a DDBMS disadvantage?
Antworten
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Processor independence
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User-friendly interface
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Security
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Faster data access
Frage 10
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What feature is a DDBMS advantage?
Frage 11
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A database is composed of several parts known as database ____.
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sections
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fragments
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partitions
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parts
Frage 12
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Under the ____ scenario, multiple processes run on different computers sharing a single data repository.
Frage 13
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The ____ scenario describes a fully distributed DBMS with support for multiple data processors and transaction processors at multiple sites.
Frage 14
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____ distributed database systems integrate only one type of centralized DBMS over a network.
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Homogenous
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Heterogeneous
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Fully heterogeneous
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Fully homogeneous
Frage 15
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____ transparency allows the integration of several different local DBMSs under a common, or global, schema.
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Transaction
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Performance
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Distribution
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Heterogeneity
Frage 16
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The ____ contains the description of the entire database as seen by the database administrator.
Antworten
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distributed global dictionary
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distributed data dictionary
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distributed global schema
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distributed data schema
Frage 17
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____ fragmentation allows us to break a single object into two or more segments or fragments.
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Horizontal
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Vertical
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Data
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Mixed
Frage 18
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With ____ data allocation, the database is divided into several disjointed parts and stored at several sites.
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centrialized
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decentralized
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partitioned
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replicated
Frage 19
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The ____ rule requires that all copies of data fragments be identical.
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shared fragment
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mutual consistency
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horizontal fragmentation
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replication
Frage 20
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Which of the following is a problem with a centralized database?