60 terms

# chapter 3

Review questions for David Kronke's "Database Processing: Fundamentals, Design and Implementation" (10th ed)
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true
All relations are tables, but not all tables are relations.
false
A relation is a three-dimensional table.
true
A characteristic of a relation is that the cells of the relation hold a single value.
false
A characteristic of a relation is that the rows of a relation may hold identical values.
false
The columns of a relation are sometimes called "tuples."
false
A tuple is a group of one or more columns that uniquely identifies a row.
true
Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.
false
The functional dependency noted as A B, means that the value of A can be determined from the value of B.
false
In the functional dependency shown as A B, B is the determinant.
true
Functional dependencies can involve groups of attributes.
true
A determinant of a functional dependency may or may not be unique in a relation.
true
A row can be uniquely identified by a key.
true
A key can be composed of a group of attributes taken together.
false
It is possible to have a relation that does not have a key.
false
A relation can have only one candidate key.
false
Surrogate keys usually slow performance.
true
Surrogate keys are normally not shown on forms or reports.
false
A constraint that requires an instance of an entity to exist in one relation before it can be referenced in another relation is called an insertion anomaly.
true
A referential integrity constraint limits the values of a foreign key.
false
If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
true
Undesirable consequences of changing the data in a relation are called "modification anomalies."
true
A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.
true
Relations are classified into "normal forms" based on the types of modification anomalies that they are vulnerable to.
false
Any table that meets the definition of a relation is in 2NF.
true
A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key.
true
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.
true
Breaking a relation into two relations may create the need for a referential integrity constraint to be defined between the two relations.
true
A multivalued dependency exists when a determinant is matched to a set of values.
true
The multivalued dependency noted as A --> -->B, means that the value of A determines a set of values of B.
true
A relation is in 4NF when multivalued dependencies are isolated in their own relation.
relation
A(n) _______ is a table composed of columns and rows.
tuple
In relational terms as defined by E.F. Codd, a row is called a(n) ________.
attribute
In relational terms as defined by E.F. Codd, a column is called a(n) _________.
functional dependency
A(n) __________ is a relationship between attributes such that if we know the value of one attribute, we can determine the value of the other attribute.
functionally dependent
If by knowing the value of A, we can find the value of B, then we would say thatB is ________ on A.
determinant
In functional dependencies, the attribute whose value is known or given is referred to as the ________ .
composite determinant
Given the functional dependency (A, B) --> C, the attributes (A, B) are referred to as a ____________.
A --> B, A --> C
Given the functional dependency A --> (B, C), then it is true that _______ and___________ .
A -->C, B --> C
Given the functional dependency (A, B) --> C, then it is not true that _______ and ________ .
B --> A
Given the functional dependency A --> B, it is not necessarily true that _________ .
key
A(n) _______ is a combination of one or more columns that is used to identify particular rows in a relation.
composite key
A(n) ___________ is a group of attributes that uniquely identifies a row.
candidate key
A(n) _____________is one of a group of keys that may serve as the primary key in a relation.
primary key
A(n) _______ is a candidate key that has been selected to uniquely identify rows in a relation.
primary key
A(n) relation or table has only one __________ .
surrogate key
A(n) ___________ is an artificial column that is added to a relation to be its primary key.
foreign key
A(n) ___________ is one or more columns in one relation that also are the primary key in another table.
referential integrity constraint
A(n) ___________________ is used to make sure the values of a foreign key match a valid value of a primary key.
modification anomalies
For some relations, changing the data can have undesirable consequences called __________________.
normal forms
Relations are categorized into ____________ where the categorization is based on the problems the relation has.
relation
Any table that meets the definition of a(n) ___________is said to be in first normal form.
INF
If a table is a relation then it is in __________ .
Boyce-Codd
A defining requirement for _____________ normal form is that every determinant must be a candidate key.
determinant
A relation is in BCNF if every _____________ is a candidate key.
candidate key
A relation is in BCNF if every determinant is a(n) ____________ .
constraint
Domain/key normal form requires that every __________ be a logical consequence of the definition of domains and keys.
domain/key
A relation that is in __________ normal form is assured to be free from all anomalies.
referential integrity
Every time we break up a relation during the normalization process, we may have to create ___________ constraints.
multivalued dependencies
A relation is in 4NF if it is in BCNF and it has no ___________________.
theme
When designing or normalizing relations, each relation should have only one ________ .