Ch 3 T/F
TRUE
A primary key is a candidate key that has been selected to uniquely identify rows in a relation.
TRUE
A referential integrity constraint limits the values of a foreign key.
FALSE
A relation can have only one candidate key.
TRUE
A relation is in 2NF if and only if it is in 1NF and all non-key attributes are determined by the entire primary key.
TRUE
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.
TRUE
A relation is in 4NF when multivalued dependencies are isolated in their own relation.
TRUE
A row can be uniquely identified by a key.
TRUE
A surrogate key is an artificial column that is added to a relation to be its primary key.
FALSE
A defining requirement for Boyce-Codd Normal Form (BCNF) is that every candidate key must be a determinant.
TRUE
A determinant of a functional dependency may or may not be unique in a relation.
TRUE
A foreign key is one or more columns in one relation that also is the primary key in another table.
TRUE
A multivalued dependency exists when a determinant is matched to a set of values.
TRUE
A referential integrity constraint is used to make sure the values of a foreign key match a valid value of a primary key.
TRUE
A relation is a table composed of columns and rows.
FALSE
A relation is a table that has special restrictions on it.
TRUE
A relation is in 4NF if it is in BCNF and it has no multivalued dependencies.
TRUE
A relation is in Boyce-Codd Normal Form (BCNF) if and only if it is in 3NF and every determinant is a candidate key.
TRUE
A relation that is in domain/key normal form is assured to be free from all anomalies.
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
TRUE
An attribute is considered to be a non-key attribute when it is a non-prime attribute, which means that the attribute is not contained in any candidate key.
FALSE
Any table that meets the definition of a relation is in 2NF.
TRUE
Any table that meets the definition of a relation is said to be in first normal form (1NF).
TRUE
Attribute Y is functionally dependent on attribute X if the value of attribute X determines the value of Y.
TRUE
Domain/key normal form requires that every constraint be a logical consequence of the definition of domains and keys.
FALSE
If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
TRUE
If by knowing the value of A we can find the value of B, then we would say that B is functionally dependent on A.
TRUE
In functional dependencies, the attribute whose value is known or given is referred to as the determinant.
TRUE
In relational terms as defined by E.F. Codd, a column is called an attribute.
TRUE
In relational terms as defined by E.F. Codd, a row is called a tuple.
FALSE
In the functional dependency shown as A → B, B is the determinant.
TRUE
Relations are classified into normal forms based on the types of modification anomalies that they are vulnerable to.
TRUE
When designing or normalizing relations, each relation should have only one theme.
TRUE
Functional dependencies can involve groups of attributes.
TRUE
A candidate key is one of a group of keys that may serve as the primary key in a relation.
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 combination key is a group of attributes that uniquely identifies a row.
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 functional dependency is a relationship between attributes such that if we know the value of one attribute, we can determine the value of the other attribute.
TRUE
A key can be composed of a group of attributes taken together.
TRUE
A key is a combination of one or more columns that is used to identify particular rows in a relation.
FALSE
It is possible to have a relation that does not have a key.
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 condition that a non-key attribute determines another non-key attribute is known as transitive dependency.
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.
FALSE
Candidate keys are called interlocking candidate keys when they share one or more attributes.
TRUE
Every time we break up a relation during the normalization process, we may have to create a referential integrity constraint
TRUE
Given the functional dependency (A, B) → C, the attributes (A, B) are referred to as a composite determinant.
FALSE
Given the functional dependency (A, B) → C, then it is true that A → C and B → C
TRUE
Given the functional dependency A → (B, C), then it is true that A → B and A → C.
FALSE
Given the functional dependency A → B, then it is necessarily true that B → A.
