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Exam 3: The Relational Database Model

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Question 41

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

A) entity
B) duplicate
C) synonym
D) homonym

E) B) and D)
F) A) and D)

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Question 42

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

A) True
B) False

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Question 43

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

You can think of a table as a persistent representation of a logical relation.

Fortunately,the problems inherent in the ____________________ relationship can easily be avoided by creating a composite entity.

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

As rare as 1:1 relationships should be,certain conditions absolutely require their use.

A left outer join on tables CUSTOMER and AGENT yields all of the rows in the CUSTOMER table,including those that do not have a matching value in the AGENT table

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

____ yields only the rows that appear in both tables.

No data entry at all is known as a(n) ____.

A proper understanding of the concept and use of keys in a relational database model is very important.

____________________ joins are especially useful when you are trying to determine what value(s)in related tables cause(s)referential integrity problems.

All primary key entries are unique,and no part of a primary key may be ____.

The following example exhibits ____________________ integrity: The CUSTOMER table's primary key is CUS_CODE.The CUSTOMER primary key column has no null entries,and all entries are unique.Similarly,the AGENT table's primary key is AGENT_CODE,and this primary key column also is free of null entries.

The DIFFERENCE operator subtracts one table from the other.

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.

____,also known as RESTRICT,yields values for all rows found in a table that satisfy a given condition.

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.

A(n) ____ is an ordered arrangement of keys and pointers.