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Exam 3: The Relational Model and Normalization

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Question 51

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All relations are tables,but not all tables are relations.

A) True
B) False

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Question 52

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It is possible to have a relation that does not have a key.

A) True
B) False

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Question 53

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A relation is in 3NF if and only if it is in 2NF and there are no non-key attributes determined by another non-key attribute.

A candidate key is one of a group of keys that may serve as the primary key in a relation.

Referential integrity constraints are used to limit the possible values of a ________.

Undesirable consequences of changing the data in a relation are called modification anomalies.

The essence of normalization is taking a relation that is not in BCNF and breaking it into multiple relations such that each one is in BCNF.

Briefly describe the various tasks of the primary key.

Distinguish between the primary key and a candidate key.

A relation is a table composed of columns and rows.

Explain the essence of normalization that is implemented through the use of normal forms.

A relation is in Boyce-Codd Normal Form (BCNF)if and only if it is in 3NF and every determinant is a candidate key.

The condition that a non-key attribute determines another non-key attribute is known as transitive dependency.

A combination key is a group of attributes that uniquely identifies a row.

Surrogate keys are normally not shown on forms or reports.

A key consisting of one or more columns that is a primary key in another relation is a ________.

Given the functional dependency (A, B) → C, then ________.

A tuple is a group of one or more columns that uniquely identifies a row.

If the removal of facts about one entity results in the unintentional loss of data about another entity,this is referred to as a(n) ________.

A relation is in 4NF if it is in BCNF and it has no multivalued dependencies.