In enterprise data modeling, which is incorrect?
Answer: B
Correct answer: You implement the new database.
Enterprise data modelling is a planning activity: reviewing the current systems, describing the data at a high level of abstraction, and identifying the database projects worth doing. Implementation comes several steps later, after conceptual, logical and physical design, and is not part of it.
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Which of the following database activities require a specific knowledge of a DBMS?
Answer: D
Correct answer: Physical database design and definition
Physical design is where the choice of product finally matters: indexes, file organisations, data types, storage parameters and tuning options are all specific to the DBMS in use. Everything above it - enterprise, conceptual and logical design - is deliberately kept independent of any particular product.
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User views are included as part of which schema?
Answer: C
Correct answer: External
An external schema is the view a particular user group has of the database - the subset they may see, presented in the form that suits them. Several external schemas sit over one conceptual schema, which is what allows different groups to be given different views of the same data.
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Whose role is it to determine the requirements and design for a database?
Answer: A
Correct answer: Database analysts
Determining requirements and producing the design is analysis and design work, and it is the database analyst’s role. The database administrator is responsible for the database in operation - installation, security, backup, tuning and availability - which is a distinct set of duties.
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There is one physical schema for each logical schema.
Answer: A
Correct answer: True
The three-schema architecture pairs one internal schema with one conceptual schema, so a single logical structure is realised by a single physical arrangement. Many external schemas may sit above the conceptual one, which is where the multiplicity in the architecture lies.
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The most important reason for data architecture is reliability.
Answer: B
Correct answer: False
Data architecture exists chiefly to give the organisation a consistent, shared and integrated view of its data, so that the same fact means the same thing everywhere and systems can work together. Reliability is a property of the implementation, achieved by other means and not the reason for the architecture.
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The systems development life cycle cannot be used with database implementation.
Answer: B
Correct answer: False
The systems development life cycle applies to database development as it does to any system development, and the database steps map onto its phases - planning, analysis, design, implementation and maintenance. Prototyping and other approaches are used as well, but the life cycle is not excluded.
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Enterprise data modeling typically occurs during information systems planning.
Answer: A
Correct answer: True
Enterprise data modelling is part of information systems planning: it produces the high-level view of the organisation’s data and identifies which database projects should be undertaken. Doing it at planning time is what allows the projects that follow to fit together rather than overlap.
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During logical database design, the conceptual data model is transformed into a logical data model which describes the data in terms of a specific data management technology.
Answer: A
Correct answer: True
This is exactly the boundary between the two stages. The conceptual model is independent of any technology; logical design converts it into the structures of a particular technology - relations for a relational database, classes for an object one - but still without regard to a specific product’s physical options.
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A conceptual schema is usually depicted in graphical format using E-R or object-modeling notations.
Answer: A
Correct answer: True
A conceptual schema is drawn, not written, because its audience includes people who must validate it and who are not database specialists. Entity-relationship or object notation makes the entities, attributes and relationships visible at a glance, which is what makes review by users possible.
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