Wgu C170 Data Management Applications Exam Questions
With Detailed Answers
Denormalization
A process by which a table is changed from a higher-level normal form to a lower-level
normal form, usually to increase processing speed.
Functional dependence
The attribute B is fully functionally dependent on the attribute A if each value
of A determines one and only one value of B. Written as: A → B
In this case, the attribute A is known as the determinant attribute, and the attribute B is
known as the dependent attribute.
Partial dependency
A condition in which an attribute is dependent on only a portion (subset) of the primary key.
Transitive dependency
A condition in which an attribute is dependent on another attribute that is not part of the
primary key.
Repeating group
In a relation, a characteristic describing a group of multiple entries of the same type for a
single key attribute occurrence. For example, a car can have multiple colors for its top,
interior, bottom, trim, and so on.
Dependency diagram
A representation of all data dependencies (primary key, partial, or transitive) within a table.
First Normal Form (1NF)
This form describes a relation depicted in tabular format, with no repeating groups, no
multivalued attributes and a primary key identified. All nonkey attributes in the relation are
dependent on the primary key.
Second normal form (2NF)
In this form, a relation has no partial dependencies (dependencies in only part of the
primary key). This form can contain transitive dependencies.
Third normal form (3NF)
,A table is in this form when no nonkey attribute is functionally dependent on another nonkey
attribute; that is, it cannot include transitive dependencies.
Surrogate key
An artificial PK introduced by the designer with the purpose of simplifying the assignment of
primary keys to tables. They are usually numeric, they are often generated automatically by
the DBMS, they are free of semantic content (they have no special meaning), and they are
usually hidden from the end users.
Atomic attribute
An attribute that cannot be further subdivided to produce meaningful components. For
example, a person's last name attribute cannot be meaningfully subdivided.
Atomicity
Not being able to be divided into smaller units. Leads to more flexible queries.
Granularity
The level of detail represented by the values stored in a table's row. Data stored at its
lowest level of _________ is said to be atomic data.
Fourth Normal Form (4NF)
A table is in this form if it contains no multiple independent sets of multivalued
dependencies. No row may contain two or more multivalued facts about an entity.
Relational catalog
The special internal database where the query optimizer finds information.
Domain
In data modeling, the construct used to organize and describe an attribute's set of possible
values.
Primary key (PK)
An identifier composed of one or more attributes that uniquely identifies a row. Also, a
candidate key selected as a unique entity identifier. A minimal superkey.
Key
One or more attributes that determine other attributes.
Determination
, The role of a key. In the context of a database table, the statement "A determines B"
indicates that knowing the value of attribute A means that the value of attribute B can be
looked up.
Determinant
Any attribute in a specific row whose value directly determines other values in that row.
Dependent
An attribute whose value is determined by another attribute.
Full functional dependence
A condition in which an attribute is functionally dependent on a composite key but not on any
subset of the key.
Composite key
A multiple-attribute key.
Key attributes
The attributes that form a primary key
Superkey
An attribute or attributes that uniquely identify each entity in a table.
Candidate key
A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a
superkey.
Entity integrity
The property of a relational table that guarantees each entity has a unique value in a
primary key and that the key has no null values.
Null
The absence of an attribute value.
Foreign key
An attribute or attributes in one table whose values must match the primary key in another
table or whose values must be null.
Referential integrity
A condition by which a dependent table's foreign key must have either a null entry or a
matching entry in the related table.
Secondary key
A key used strictly for data retrieval purposes. For example, the combination of last name,
first name, middle initial, and telephone number will probably match the appropriate table
row. Also called an alternate key.
With Detailed Answers
Denormalization
A process by which a table is changed from a higher-level normal form to a lower-level
normal form, usually to increase processing speed.
Functional dependence
The attribute B is fully functionally dependent on the attribute A if each value
of A determines one and only one value of B. Written as: A → B
In this case, the attribute A is known as the determinant attribute, and the attribute B is
known as the dependent attribute.
Partial dependency
A condition in which an attribute is dependent on only a portion (subset) of the primary key.
Transitive dependency
A condition in which an attribute is dependent on another attribute that is not part of the
primary key.
Repeating group
In a relation, a characteristic describing a group of multiple entries of the same type for a
single key attribute occurrence. For example, a car can have multiple colors for its top,
interior, bottom, trim, and so on.
Dependency diagram
A representation of all data dependencies (primary key, partial, or transitive) within a table.
First Normal Form (1NF)
This form describes a relation depicted in tabular format, with no repeating groups, no
multivalued attributes and a primary key identified. All nonkey attributes in the relation are
dependent on the primary key.
Second normal form (2NF)
In this form, a relation has no partial dependencies (dependencies in only part of the
primary key). This form can contain transitive dependencies.
Third normal form (3NF)
,A table is in this form when no nonkey attribute is functionally dependent on another nonkey
attribute; that is, it cannot include transitive dependencies.
Surrogate key
An artificial PK introduced by the designer with the purpose of simplifying the assignment of
primary keys to tables. They are usually numeric, they are often generated automatically by
the DBMS, they are free of semantic content (they have no special meaning), and they are
usually hidden from the end users.
Atomic attribute
An attribute that cannot be further subdivided to produce meaningful components. For
example, a person's last name attribute cannot be meaningfully subdivided.
Atomicity
Not being able to be divided into smaller units. Leads to more flexible queries.
Granularity
The level of detail represented by the values stored in a table's row. Data stored at its
lowest level of _________ is said to be atomic data.
Fourth Normal Form (4NF)
A table is in this form if it contains no multiple independent sets of multivalued
dependencies. No row may contain two or more multivalued facts about an entity.
Relational catalog
The special internal database where the query optimizer finds information.
Domain
In data modeling, the construct used to organize and describe an attribute's set of possible
values.
Primary key (PK)
An identifier composed of one or more attributes that uniquely identifies a row. Also, a
candidate key selected as a unique entity identifier. A minimal superkey.
Key
One or more attributes that determine other attributes.
Determination
, The role of a key. In the context of a database table, the statement "A determines B"
indicates that knowing the value of attribute A means that the value of attribute B can be
looked up.
Determinant
Any attribute in a specific row whose value directly determines other values in that row.
Dependent
An attribute whose value is determined by another attribute.
Full functional dependence
A condition in which an attribute is functionally dependent on a composite key but not on any
subset of the key.
Composite key
A multiple-attribute key.
Key attributes
The attributes that form a primary key
Superkey
An attribute or attributes that uniquely identify each entity in a table.
Candidate key
A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a
superkey.
Entity integrity
The property of a relational table that guarantees each entity has a unique value in a
primary key and that the key has no null values.
Null
The absence of an attribute value.
Foreign key
An attribute or attributes in one table whose values must match the primary key in another
table or whose values must be null.
Referential integrity
A condition by which a dependent table's foreign key must have either a null entry or a
matching entry in the related table.
Secondary key
A key used strictly for data retrieval purposes. For example, the combination of last name,
first name, middle initial, and telephone number will probably match the appropriate table
row. Also called an alternate key.
