CS Quiz 1

A fundamental characteristic of the database approach is that the database system contains not only the database itself but also a definition or description of the database structure and constraints. (a) True (b) False

A

Choose the correct phrase to fill in the blank: The data in the database at a particular point in time is called a ________. (a) database state (b) database schema (c) meta state (d) logical database

A

Data definition view definition and data manipulation are handled in one integrated language known as SQL in current database management systems based on the relational data model. (a) True (b) False

A

External schemas a) are views tailored to particular users b) are specified with ER models c) specify the storage structure of the data d) None of the above

A

The goal of the three schema database architecture is to separate the user applications from the physical details of a database. (a) True (b) False

A

When details about data location storage encoding and data compression are hidden from the conceptual schema we can say that the DBMS supports physical data independence. (a) True (b) False

A

Which is true? (a) tuples within a table are not ordered, but attributes within a tuple are ordered (b) tuples within a table are not ordered, and attributes within a tuple are not ordered (c) tuples within a table are ordered, but attributes within a tuple are not ordered (d) tuples within a table are ordered, and attributes within a tuple are ordered

A

Choose the correct phrase to fill in the blank: The characteristic provided by DBMSs and data models that allows program-data independence and program-operation independence is _______. (a) data redundancy (b) data abstraction (c) transaction recovery (d) concurrency control

B

No attribute of a primary key can be null. What is the name of this constraint? (a) key constraint (b) entity integrity constraint (c) referentialintegrityconstraint (d) domain constraint

B

SQL is considered what type of language? a) A data definition language b) A query language c) Both a) and b) d) None of the above.

B

The foreign key constraint requires which of the following to be true? (a) the foreign key value in the referencing relation cannot be null (b) the foreign key value in the referencing relation must be null or an existing primary key in the referenced relation (c) the foreign key in the referencing relation must consist of a single attribute (d) the foreign key in the referencing relation must be a superkey of the referenced relation

B

Which of the following are advantages of the database approach? a) Tight coupling between data and programs b) Multiple views of the data for different users c) Non-changeable schemas d) All of the above

B

Which of the following is an example of a representational data model? (a) entity relationship data model (b) relational data model (c) access path model (d) none of the above

B

Which of the following is an important aspect of the three schema database architecture? (a) It allows end-users to directly access the internal schema in their data requests. (b) It provides the capability for the DBMS to map a data request at a higher level (application oriented) to a request at a lower level (data storage specific) in the 3 schema architecture. (c) It provides a runtime database processor. (d) none of the above

B

Which of the following statements is true? (a) End users of a database must know details about the storage structures used by the database system. (b) Application programmers are responsible for the physical design of the database. (c) The database administrator is responsible for authorizing access to the database and for maintaining an adequate database system performance level. (d) All of the above

C

Suppose we change the conceptual schema to add a constraint to the database. The applications and the external schemas for the database do not have to be changed. This is an example of what concept? (a) program operation independence (b) physical data independence (c) logical data independence (d) procedural independence

C

A data model is used to describe the structure of a database. Which of the following concepts are included in the structure/schema of a database? (a) data types (b) relationships (c) constraints (d) All of the above

D

Which of the following is true about a high-level data manipulation language? (a) It can be embedded in a general purpose programming language. (b) It can be used as a standalone query language. (c) It is considered to be procedural since it retrieves records individually. (d) Both (a) and (b)

D

Which of the following is true about the query optimizer component of a DBMS? (a) It involves reordering of operations for a given query (b) It involves elimination of redundancies embedded in queries (c ) It involves use of indexes to make queries run faster (d) All of the above

D

Which statement is true about views in database systems? (a) A view may be a subset of the database. (b) A view may contain virtual data that is derived from the database but is not explicitly stored. (c) Multiple views of a database may exist depending on the different perspectives of the users. (d) All of the above

D