chapter 3
true
A referential integrity constraint limits the values of a foreign key.
false
A relation can have only one candidate key.
false
A relation is a three-dimensional table.
multivalued dependencies
A relation is in 4NF if it is in BCNF and it has no ___________________.
true
A relation is in 4NF when multivalued dependencies are isolated in their own relation.
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) ____________ .
true
A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key.
domain/key
A relation that is in __________ normal form is assured to be free from all anomalies.
true
A row can be uniquely identified by a key.
false
A tuple is a group of one or more columns that uniquely identifies a row.
primary key
A(n) _______ is a candidate key that has been selected to uniquely identify rows in a relation.
key
A(n) _______ is a combination of one or more columns that is used to identify particular rows in a relation.
relation
A(n) _______ is a table composed of columns and rows.
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.
composite key
A(n) ___________ is a group of attributes that uniquely identifies a row.
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.
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) relation or table has only one __________ .
constraint
Domain/key normal form requires that every __________ be a logical consequence of the definition of domains and keys.
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
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.
Boyce-Codd
A defining requirement for _____________ normal form is that every determinant must be a candidate key.
true
A deletion anomaly exists when deleting data about one entity results in the loss of data about another entity.
true
A determinant of a functional dependency may or may not be unique in a relation.
true
A key can be composed of a group of attributes taken together.
attribute
In relational terms as defined by E.F. Codd, a column is called a(n) _________.
tuple
In relational terms as defined by E.F. Codd, a row is called a(n) ________.
false
In the functional dependency shown as A B, B is the determinant.
false
It is possible to have a relation that does not have a key.
normal forms
Relations are categorized into ____________ where the categorization is based on the problems the relation has.
true
Relations are classified into "normal forms" based on the types of modification anomalies that they are vulnerable to.
true
Surrogate keys are normally not shown on forms or reports.
false
Surrogate keys usually slow performance.
false
The columns of a relation are sometimes called "tuples."
true
A multivalued dependency exists when a determinant is matched to a set of values.
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.
false
The functional dependency noted as A B, means that the value of A can be determined from the value of B.
true
The multivalued dependency noted as A --> -->B, means that the value of A determines a set of values of B.
true
Undesirable consequences of changing the data in a relation are called "modification anomalies."
theme
When designing or normalizing relations, each relation should have only one ________ .
true
All relations are tables, but not all tables are relations.
determinant
In functional dependencies, the attribute whose value is known or given is referred to as the ________ .
false
Any table that meets the definition of a relation is in 2NF.
relation
Any table that meets the definition of a(n) ___________is said to be in first normal form.
true
Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.
true
Breaking a relation into two relations may create the need for a referential integrity constraint to be defined between the two relations.
referential integrity
Every time we break up a relation during the normalization process, we may have to create ___________ constraints.
modification anomalies
For some relations, changing the data can have undesirable consequences called __________________.
true
Functional dependencies can involve groups of attributes.
composite determinant
Given the functional dependency (A, B) --> C, the attributes (A, B) are referred to as a ____________.
A -->C, B --> C
Given the functional dependency (A, B) --> C, then it is not true that _______ and ________ .
A --> B, A --> C
Given the functional dependency A --> (B, C), then it is true that _______ and___________ .
B --> A
Given the functional dependency A --> B, it is not necessarily true that _________ .
INF
If a table is a relation then it is in __________ .
false
If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
functionally dependent
If by knowing the value of A, we can find the value of B, then we would say thatB is ________ on A.
