Which of the following is an advantage of view?
Answer: D
Correct answer: All of the above
A view gives all three. Security: users can be granted access to the view and not to the underlying table, so they see only certain rows or columns. Derived columns: a view can compute values that are not stored. Simplicity: a complex join can be defined once and then queried as though it were a single table.
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In a database, data is stored in spreadsheets which have rows and columns.
Answer: B
Correct answer: False
Data is stored in tables (relations), which have rows and columns. A spreadsheet also has rows and columns, but that resemblance is superficial: a table has a defined structure, typed columns, keys, and relationships to other tables, and is managed by a DBMS that enforces all of it.
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It is better to use files than a DBMS when there are
Answer: B
Correct answer: Stringent real-time requirements
A DBMS adds layers - query processing, locking, logging - and with them latency that is hard to bound. Where an application must guarantee a response within a few microseconds, direct file access is more predictable. The other two options are arguments for a DBMS, not against: concurrent access and complex relationships are exactly what it exists to manage.
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Which of the following products implemented the CODASYL DBTG model?
Answer: A
Correct answer: IDMS
IDMS implemented the CODASYL DBTG network model, the dominant pre-relational approach, in which records are linked by explicit sets and navigated pointer by pointer. It is still in use on mainframes. DB2 is relational; dBase-II and R:base were PC products.
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The DBMS ranked as being the "hardest to use" in the text is Microsoft's SQL Server.
Answer: B
Correct answer: False
The one ranked hardest to use is Oracle, not SQL Server. SQL Server sits between Access and Oracle: an enterprise product, but a more approachable one to administer.
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