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WorksheetsPretest 1 PDBMS
Total questions: 12
Worksheet time: 20mins
Which statement is not correct?
The file-based approach to data management causes the same information to be stored separately for different applications.
In a file-based approach to data management, the data definitions are included in each application separately.
In a file-based approach to data management, different applications could be using older and newer versions of the same data.
In a file-based approach to data management, a change in the structure of a data file is easily handled because each application has its own data files.
Which statement is not correct?
In a database approach, applications don’t have their own files, but all applications access the same version of the data by interfacing with the DBMS.
In a database approach, the data definitions or metadata are stored in the applications accessing the data.
In a database approach, there is typically less storage needed compared to the file approach.
In a database approach, maintenance of data and metadata is easier.
Which statement is not correct?
In a file-based approach, every application has its own query and access procedures, even if they want to access the same data.
SQL is a database language to manage DBMSs without having to write a substantial amount of programming code.
SQL is a database language that focuses on how to access and retrieve the data.
SQL is a database language that allows different applications to access different subsets of the data necessary for each application.
Which statement is not correct?
In a conceptual data model, the data requirements from the business should be captured and modeled.
A conceptual data model is implementation-dependent.
A logical data model translates the conceptual data model to a specific implementation environment.
Examples of implementations of logical data models are hierarchical, CODASYL, relational, or object-oriented models.
Complete the following sentence, choosing the right words in positions A and B. A(n) …A… data model is the mapping of a(n) …B… data model to a model that describes which data are stored where and in what format.
A: internal, B: logical.
A: conceptual, B: internal.
A: logical, B: internal.
A: logical, B: conceptual.
What concept specifies the various data items, their characteristics, and relationships, constraints, storage details, etc. and is specified during the database design?
Database model.
Catalog
Database state
None of the above
Which statement regarding the database state is correct?
The database state represents the data in the database when the database is first created
The database state changes when data are updated or removed
The database state specifies the various data items, their characteristics, and relationships, and is specified during the database design
The database state is stored in the catalog
Complete this sentence: In the three-layer architecture, between the external layer and the conceptual/logical layer, there is …
physical data independence
logical data independence
no independence, they are basically the same thing
the internal layer
Which statement is correct?
Statement A: The middle layer of the three-layer architecture consists of both the conceptual data model and the logical data model. The logical data model is physically implemented in the internal layer.
Statement B: The top level of the three-layer architecture is the external layer. Views for one or more applications always offer a window on the complete logical model.
Only sentence A is right
Only sentence B is right
Sentences A and B are right
Neither A nor B is right
Which statement is correct?
Statement A: DDL is the language used to define the logical data model, but no other data models.
Statement B: SQL is a DML language to retrieve, insert, delete, and modify data. It is stored in the catalog.
Only A
Only B
A and B
Neither A nor B
Which statement is correct?
Statement A: Physical data independence implies that neither the applications nor the views or logical data model must be changed when changes are made to the data storage specifications in the internal data model.
Statement B: Logical data independence implies that software applications are minimally affected by changes in the conceptual or logical data model.
Only A
Only B
A and B
Neither A nor B
Consider this rule: “An employee of a department can never earn more than the manager of the department.” This is an example of a:
syntactical integrity rule
semantical integrity rule
