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Exam 3: The Relational Database Model

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Question 31

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The constraint can be placed on a column to ensure that every row in the table has a value for that column.

A) UNIQUE
B) NOT NULL
C) VALUE
D) EMPTY

E) C) and D)
F) None of the above

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Question 32

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To be considered minimally relational, the DBMS must support the key relational operators , PROJECT, and JOIN.

A) INTERSECT
B) UNION
C) DIFFERENCE
D) SELECT

E) A) and C)
F) A) and D)

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Question 33

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In a natural join, the column on which the join was made occurs twice in the new table.

Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.

The practical significance of taking the logical view of a database is that it serves as a reminder of the simple file concept of data storage.

Define entity integrity. What are the two requirements to ensure entity integrity?

A primary key is a(n) key chosen to be the primary means by which rows of a table are uniquely identified.

Proper data design requires carefully defined and controlled data redundancies to function properly.

Describe the use of null values in a database.

The relational operators have the property of ; that is, the use of relational algebra operators on existing relations (tables) produces new relations.

The one-to-many (1:M) relationship is easily implemented in the relational model by putting the foreign key of the "1" side in the table of the "many" side as a primary key.

logic, used extensively in mathematics, provides a framework in which an assertion (statement of fact) can be verified as either True or false.

Another name for a composite entity is a(n) entity.

A contains at least all of the attribute names and characteristics for each table in the system.

A(n) links tables on the basis of an equality condition that compares specified columns of each table.

The CUSTOMER table's primary key is CUS_CODE. The CUSTOMER primary key column has no null entries, and all entries are unique. This is an example of integrity.

A(n) is an orderly arrangement used to logically access rows in a table.

The relationship should be rare in any relational database design.

A(n) provides a detailed description of all tables found within the user/designer-created database.

A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind.