chapter 3
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.
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.
true
A multivalued dependency exists when a determinant is matched to a set of values.
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.
true
A relation is in 4NF when multivalued dependencies are isolated in their own relation.
true
A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key.
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.
true
All relations are tables, but not all tables are relations.
false
Any table that meets the definition of a relation is in 2NF.
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.
true
Functional dependencies can involve groups of attributes.
false
If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
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.
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
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."
