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Exam 3: The Relational Database Model

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Question 41

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What is a key and why is it important in the relational model?

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In the relational model,keys are importa...

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Question 42

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The ____________________ catalog can be described as a detailed system data dictionary that describes all objects within the database,including data about table names,the table's creator and creation date,the number of columns in each table,the data type corresponding to each column,index filenames,index creators,authorized users,and access privileges.

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Question 43

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

The attribute B is ____ the attribute A if each value in column A determines one and only one value in column B.

The ____ relationship should be rare in any relational database design.

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

What are the characteristics of a relational table?

Another name for a composite entity is a ____ entity.

A foreign key must exist in both tables that have a relationship.

If the attribute (B)is functionally dependent on a composite key (A)but not on any subset of that composite key,the attribute (B)is fully functionally dependent on (A).

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

The equijoin takes its name from the comparison operator ____ used in the condition.

The logical view of the relational database is facilitated by the creation of data relationships based on a logical construct known as a(n)____________________.

The idea of determination is unique to the database environment.

RDBMSs enforce integrity rules automatically.

Tables must have the same attribute characteristics (the columns and domains must be compatible)to be used in a UNION.

Because the relational model uses attribute values to establish relationships among tables,many database users correctly assume that the term relation refers to such relationships.

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.

In the relational model,____________________ are important because they are used to ensure that each row in a table is uniquely identifiable.

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