ise224 ch3
Which of the following is NOT true about the functional dependency A → (X, Y)? A) X is functionally dependent on A. B) A determines Y. C) X and Y together determine A. D) X and Y are functionally dependent on A.
C
Which of the following is true about the functional dependency (A, B) → (C, D)? A) A is the determinant of C. B) A and B together are determined by C and D together. C) A and B together determine D. D) C and D together determine A.
C
Which of the following is true for a relation? A) Entities in a column vary as to kind. B) The order of the columns is important. C) The order of the rows is unimportant. D) More than one column can use the same name.
C
A relation is also known as a(n) ________. A) table B) tuple C) relationship D) attribute
A
A table that meets the definition of a relation is in ________. A) First Normal Form B) Second Normal Form C) Third Normal Form D) Boyce-Codd Normal Form
A
Given the functional dependency (A, B) → C, then ________. A) A and B together → C B) A → C C) B → A D) Both A and B are correct
A
Having to enter facts about two entities when we want to enter facts about only one is an example of ________. A) insertion anomaly B) update anomaly C) deletion anomaly D) normalization anomaly
A
In general, each relation should have ________. A) one and only one theme B) one or more themes C) exactly two themes D) one or two themes
A
The only reason(s) for having relations is to ________. A) store instances of functional dependencies B) store equation components C) store equation results D) Both B and C are correct
A
A determinant that determines all the other columns in a relation is a ________. A) record B) surrogate key C) foreign key D) candidate key
D
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.
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 foreign key is one or more columns in one relation that also is the primary key in another table.
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.
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 referential integrity constraint limits the values of a foreign key.
TRUE
A relation is a table composed of columns and rows.
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 Boyce Codd Normal Form (BCNF) if and only if it is in 3NF and every determinant is a candidate key.
TRUE
An attribute is a non-key attribute when it is a non-prime attribute, which means that the attribute is not contained in any candidate key.
TRUE
Domain/key normal form requires that every constraint be a logical consequence of the definition of domains and keys.
TRUE
The multivalued dependency noted as A → → B, means that the value of A determines a set of values of B.
TRUE
When designing or normalizing relations, each relation should have only one theme.
TRUE
A characteristic of a relation is that the rows of a relation may hold identical values.
FALSE
A relation can have only one candidate key.
FALSE
A relation is a table that has special restrictions on it.
FALSE
A tuple is a group of one or more columns that uniquely identifies a row.
FALSE
Given the functional dependency A → B, then it is necessarily true that B → A.
FALSE
If a table meets the minimum definition of a relation, it has an effective or appropriate structure.
FALSE
It is possible to have a relation that does not have a key.
FALSE
Surrogate keys usually slow performance.
FALSE
The columns of a relation are sometimes called tuples.
FALSE
A relation is in second normal form (2NF) if and only if it is in 1NF and ________. A) all non-key attributes are determined by the entire primary key B) there are no non-key attributes determined by another non-key attribute C) every attribute is a candidate key D) every candidate key is a determinant
A
When designing a database, one of the candidate keys in a relation is selected as the ________. A) composite key B) primary key C) foreign key D) surrogate key
B
A key consisting of one or more columns that is a primary key in another relation is a ________. A) composite key B) candidate key C) foreign key D) surrogate key
C
A tuple is also known as a ________. A) table B) relation C) row D) field
C
A combination of two or more columns used to identify rows in a relation is a ________. A) record B) composite key C) foreign key D) surrogate key
B
A relation is in fourth normal form if it is in BCNF and it has no ________. A) transitive dependencies B) multivalued dependencies C) partial dependencies D) deletion dependencies
B
A relation is in third normal form (3NF) if and only if it is in 2NF and ________. A) all non-key attributes are determined by the entire primary key B) there are no non-key attributes determined by another non-key attribute C) every attribute is a candidate key D) every candidate key is a determinant
B
Saying that two entities are functionally dependent means that ________. A) the entities are always connected by a mathematical equation B) for one of the entities, if we are given the value of that entity, we can determine the value of one other entity C) for both entities, if we are given the value of one entity, we can determine the value of the other entity D) the functional dependency will have to be removed through normalization
B
A combination of one or more columns used to identify rows in a relation is a ________. A) record B) field C) key D) tuple
C
Given the functional dependency A → (B, C), A is a(n) ________. A) independent variable B) dependent variable C) determinant D) composite determinant
C
If a relation is in BCNF, and each multivalued dependency has been moved to a relation of its own, then the first relation is in ________. A) Third Normal Form B) Boyce-Codd Normal Form C) Fourth Normal Form D) Domain/key normal form
C
Referential integrity constraints are used to limit the possible values of a ________. A) composite key B) candidate key C) foreign key D) surrogate key
C
Suppose that you need to update one value of the column SalesCost in a relation. The way the relation is constructed, this value needs to be changed in three different rows. However, you only change the value in two of the rows. You have just created a(n) ________. A) normalization anomaly B) insertion anomaly C) update anomaly D) deletion anomaly
C
A ________ is used to limit the possible values of a foreign key. A) composite key B) surrogate key C) functional dependency D) referential integrity constraint
D
A relation is in Boyce-Codd normal form (BCNF) if and only if it is in 3NF and ________. A) all non-key attributes are determined by the entire primary key B) there are no non-key attributes determined by another non-key attribute C) every attribute is a candidate key D) every determinant is a candidate key
D
A relation is in domain/key normal form if ________. A) every key of the relation is a logical consequence of the definition of constraints and determinants B) every key of the relation is a logical consequence of the definition of constraints and domains C) every constraint on the relation is a logical consequence of the definition of keys and determinants D) every constraint on the relation is a logical consequence of the definition of keys and domains
D
An artificial column added to a relation to serve as the primary key is a ________. A) composite key B) candidate key C) foreign key D) surrogate key
D
An attribute is also known as a ________. A) table B) relation C) row D) column
D
Given the functional dependency (A, B) → C, (A, B) is a ________. A) dependent variable B) determinant C) composite determinant D) Both B and C are correct
D
If a table is designed so that every determinant is a candidate key, then that relation is in ________. A) First Normal Form B) Second Normal Form C) Third Normal Form D) Boyce-Codd Normal Form
D
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) normalization anomaly B) insertion anomaly C) update anomaly D) deletion anomaly
D
Which of the following is not true about a relation? A) Has rows containing data about an entity B) Has columns containing data about attributes of the entity C) Has cells that hold only a single value D) Can have two identical rows
D
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.
FALSE
Any table that meets the definition of a relation is in 2NF.
FALSE
Candidate keys are called interlocking candidate keys when they share one or more attributes.
FALSE
Given the functional dependency (A, B) → C, then it is true that A → C and B → C.
FALSE
In the functional dependency shown as A → B, B is the determinant.
FALSE
The functional dependency noted as A → B means that the value of A can be determined from the value of B.
FALSE
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 primary key is a candidate key that has been selected to uniquely identify rows in a relation.
TRUE
A relation is in 4NF if it is in BCNF and it has no multivalued dependencies.
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 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.
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.
TRUE
All relations are tables, but not all tables are relations.
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
Every time we break up a relation during the normalization process, we may have to create a referential integrity constraint.
TRUE
Functional dependencies can involve groups of attributes.
TRUE
Given the functional dependency (A, B) → C, the attributes (A, B) are referred to as a composite determinant.
TRUE
Given the functional dependency A → (B, C), then it is true that A → B and A → C.
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.
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.
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.
TRUE
Undesirable consequences of changing the data in a relation are called modification anomalies.
TRUE