Lesson 5 Flashcards
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
The transaction property that requires all parts of a transaction to be treated as a single, indivisible, logical unit of work. All parts of a transaction must be completed or the entire transaction is aborted.
Boyce-Codd normal form (BCNF)
A special type of third normal form (3NF) in which every determinant is a candidate key. A table in BCNF must be in 3NF.
determinant
Any attribute in a specific row whose value directly determines other values in that row.
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. Denormalization potentially yields data anomalies.
dependency diagram
A representation of all data dependencies (primary key, partial, or transitive) within a table.
first normal form (1NF)
The first stage in the normalization process. It describes a relation depicted in tabular format, with no repeating groups and a primary key identified. All nonkey attributes in the relation are dependent on the primary key.
fourth normal form (4NF)
A table is in 4NF if it is in 3NF and contains no multiple independent sets of multivalued dependencies.
granularity
The level of detail represented by the values stored in a table’s row. Data stored at its lowest level of granularity is said to be atomic data.
nonprime attribute
An attribute that is not part of a key.
normalization
A process that assigns attributes to entities so that data redundancies are reduced or eliminated.
partial dependency
A condition in which an attribute is dependent on only a portion (subset) 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
second normal form (2NF)
The second stage in the normalization process, in which a relation is in 1NF and there are no partial dependencies (dependencies in only part of the primary key).
third normal form (3NF)
A table is in 3NF when it is in 2NF and no nonkey attribute is functionally dependent on another nonkey attribute; that is, it cannot include transitive dependencies.
transitive dependency
A condition in which an attribute is dependent on another attribute that is not part of the primary key.
Some very specialized applications may require normalization beyond the _____.
4NF
Repeating groups must be eliminated by ensuring that each row defines a single entity. (T/F)
True
Normalization is a process that is used for changing attributes to entities. (T/F)
True
A table that has all key attributes defined, has no repeating groups, and all its attributes are dependent on the primary key is said to be in _____.
1NF
Since a partial dependency can exist only if a table’s primary key is composed of several attributes, if a table in 1NF has a single-attribute primary key, then the table is automatically in 2NF. (T/F)
True
A relational table must not contain a(n) _____.
repeating group
When designing a database, you should _____.
make sure that the table entities are normalized before table structures are created
A dependency based on only a part of a composite primary key is called a _______
partial dependency
A table is in BCNF if every determinant in the table is a candidate key. (T/F)
True
Reporting anomalies in a table can cause a multitude of problems for managers and can be fixed through application programming. (T/F)
False
It is possible for a table in 2NF to exhibit transitive dependency, where the primary key may rely on one or more nonprime attributes to functionally determine other nonprime attributes. (T/F)
True
An atomic attribute _____ .
cannot be further subdivided
Granularity refers to _____.
the level of detail represented by the values in a table’s row
Attribute A _____ attribute B if all of the rows in the table that agree in value for attribute A also agree in value for attribute B.
determines
All relational tables satisfy the ______ requirements.
1NF
From a system functionality point of view, _____ attribute values can be calculated when they are needed to write reports or invoices.
derived
The objective of normalization is to ensure that each table conforms to the concept of well-formed relations. (T/F)
True
1NF, 2NF, and 3NF are _____.
normalization stages
A table that is in 1NF and includes no partial dependencies is said to be in _____.
2NF
In the ______, no row may contain two or more multivalued facts about an entity.
4NF
Normalization is a very important database design ingredient, and the highest level is always the most desirable. (T/F)
False
________ is a process that is used for changing attributes to entities.
Normalization
A dependency of one nonprime attribute on another nonprime attribute is a partial dependency. (T/F)
False
Dependencies that are based on only a part of a composite primary key are called transitive dependencies. (T/F)
False
Data redundancy produces _____ .
data anomalies
Dependencies can be identified with the help of a dependency ______.
diagram
Before converting a table into 3NF, it is imperative that the table already be in _____.
2NF
From a structural point of view, 2NF is better than _____.
1NF
_______ is a process of organizing the data in the database to avoid insertion anomaly, data redundancy, update and deletion anomaly.
Normalization
If a table has multiple candidate keys and one of those candidate keys is a composite key, the table can have _____ based on this composite candidate key even when the primary key chosen is a single attribute.
partial dependencies
Of the following normal forms, _____ is mostly of theoretical interest.
DKNF
For most business transactional databases, we should normalize relations into _____.
3NF
All relational tables satisfy the 1NF requirements. (T/F)
True
Normalization works through a series of stages called normal forms. For most purposes in business database design, _____ stages are as high as you need to go in the normalization process.
Three
In a(n) _____ diagram, the arrows above the attributes indicate all desirable dependencies.
dependency
A(n) _____ exists when there are functional dependencies such that Y is functionally dependent on X, Z is functionally dependent on Y, and X is the primary key.
transitive dependency
Because a partial dependency can exist only when a table’s primary key is composed of several attributes, a table whose ______ key consists of only a single attribute is automatically in 2NF once it is in 1NF.
primary
The problem with transitive dependencies is that they still yield data _______, inconsistencies, and irregularities.
anomalies
A table that displays data redundancies yields _____.
anomalies
In the context of partial dependencies, data redundancies occur because every row entry requires duplication of data. (T/F)
True
Normalization works through a series of stages called normal forms. (T/F)
True
When a table contains only one candidate key, _____ are considered to be equivalent.
the 3NF and the BCNF
Dependency diagrams are very helpful in getting a bird’s eye view of all the relationships among a table’s attributes. (T/F)
True
Most designers consider the BCNF as a special case of the _____.
3NF
A dependency based on only a part of a composite primary key is known as a partial dependency. (T/F)
True
A determinant is any attribute whose value determines other values within a column. (T/F)
False
A _____ derives its name from the fact that a collection of multiple entries of the same type can exist for any single key attribute occurrence.
repeating group
An attribute that cannot be further subdivided is said to be ______.
atomic
BCNF can be violated only if the table contains more than one _____ key.
candidate
Data redundancy produces data anomalies. (T/F)
True
__________ specifies that a non-prime attribute is functionally dependent on part of a candidate key.
partial dependency
When designing a new database structure based on the business requirements of the end users, the database designer will construct a data model using a technique such as _____ ______ _______ ______.
Crow’s Foot notation ERDs
________ refers to the level of detail represented by the values stored in a table’s row.
Granularity
Improving _____ leads to more flexible queries.
atomicity
A table that is in 2NF and contains no transitive dependencies is said to be in _____.
3NF
An attribute that is part of a key is known as a(n) _____ attribute.
prime
Any attribute whose value determines other values within a row is known as a _______
determinant
Relational models view data as part of a table or collection of tables in which all key values must be identified. (T/F)
True
Any attribute that is at least part of a key is known as a
key attribute
________ is a process to help reduce the likelihood of data anomalies.
normalization
A transitive dependency is one in which an attribute is functionally dependent on another non-key attribute. (T/F)
True
Dependencies based on only a part of a composite primary key are known as _____ dependencies.
partial
Normalization produces a lower normal form. (T/F)
False
From a structural point of view, 3NF is better than _____.
2NF
