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Exam 4: Relational Model Characteristics

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Question 41

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A data dictionary contains metadata-data about data.

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Question 42

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The ____ relational type is the "relational model ideal."

A) 1:1
B) 1:M
C) M:1
D) M:N

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Question 43

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A ____ is any key that uniquely identifies each row.

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.

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

Character data can contain any character or symbol intended for mathematical manipulation.

If one department chair-a professor-can chair only one department and one department can have only one department chair, then the entities PROFESSOR and DEPARTMENT exhibit a(n) ____________________ relationship.

Describe the use of the UNION operator.

What is the system catalog?

There is never a good reason to use null values in a database.

In a database context, a(n) ____ indicates the use of different names to describe the same attribute.

In the context of a database table, the statement "A ____ B" indicates that if you know the value of attribute A, you can look up the value of attribute B.

Current relational database software generally provides only a system catalog (and not a data dictionary).

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

Codd's Rule of ____ states: If the system supports low-level access to the data, users must not be allowed to bypass the integrity rules of the database

A(n) ____ is perceived as a two-dimensional structure composed of rows and columns.

Referential and entity integrity are two names for the same thing.

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

The proper use of ____________________ keys is crucial to controlling data redundancy.

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.