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Physical Data Independence is the capacity to change the internal schema without having to change the conceptual schema.
Physical Data Independence is the capacity to change the internal schema without having to change the conceptual schema.
True
Logical Data Independence is the capacity to change the conceptual schema without having to change the external schema.
Logical Data Independence is the capacity to change the conceptual schema without having to change the external schema.
True
Physical Data Independence is not important in database design.
Physical Data Independence is not important in database design.
False
Implementation (representational) data models provide concepts that fall between the above two, used by many commercial DBMS implementations (e.g. relational data models used in many commercial systems).
Implementation (representational) data models provide concepts that fall between the above two, used by many commercial DBMS implementations (e.g. relational data models used in many commercial systems).
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In many DBMSs, the DDL is also used to define internal and external instances.
In many DBMSs, the DDL is also used to define internal and external instances.
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Three-tier Architecture Can Enhance Security because clients does not contain user interfaces and Web browsers.
Three-tier Architecture Can Enhance Security because clients does not contain user interfaces and Web browsers.
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Conceptual (high-level, semantic) data models provide concepts that describe details of how data is stored in the computer.
Conceptual (high-level, semantic) data models provide concepts that describe details of how data is stored in the computer.
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When a schema at a higher level is changed, only the mappings between this schema and middle-level schemas need to be changed in a DBMS that fully supports data independence.
When a schema at a higher level is changed, only the mappings between this schema and middle-level schemas need to be changed in a DBMS that fully supports data independence.
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