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Chapter 4 - Logical Database Design and Relational Model
Database Design
24
Other
Undergraduate 3
02/26/2018

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Term
Relation
Definition
A named two-dimensional table of data.
Term
Primary Key
Definition
An attribute or a combination of attributes that uniquely identifies each row in a relation.
Term
Composite Key
Definition
A primary key that consists of more than one attribute.
Term
Foreign Key
Definition
An attribute in a relation that serves as a primary key of another relation in the same database.
Term
Null
Definition
A value that may be assigned to a attribute when no other value applies or when the applicable value is unknown.
Term
Entity Integrity Rule
Definition
A rule that states that no primary key attribute (or component of a primary key attribute) may be null.
Term
Referential Integrity Constraint
Definition
A rule that states that either each foreign key value must match a primary key value in another relation or the foreign key value must be null.
Term
Well-structured Relation
Definition
A relation that contains minimal redundancy and allows users to insert, modify and delete the rows in a table without error or inconsistencies.
Term
Anomaly
Definition
An error or inconsistency that may result when a user attempts to update a table that contains redundant data. The three types of anomalies are insertion, deletion, and modification anomalies.
Term
Surrogate Primary Key
Definition
A serial number or other system-assigned primary key for a relation.
Term
Recursive Foreign Key
Definition
A foreign key in a relation that references the primary key values of the same relation.
Term
Normalization
Definition
The process of decomposing relations with anomalies to produce smaller, well-structured relations.
Term
Normal Form
Definition
A state of a relation that requires that certain rules regarding relationships between attributes (or functional dependencies) are satisfied.
Term
Functional Dependency
Definition
A constraint between two attributes in which the value of one attribute is determined by the value of another attribute.
Term
Determinant
Definition
The attribute on the left side of the arrow in a functional dependancy
Term
Candidate Key
Definition
An attribute, or combination of attributes, that uniquely identifies a row in a relation.
Term
First Normal Form (1NF)
Definition
A relation that has a primary key and in which there are no repeating groups.
Term
Second Normal Form (2NF)
Definition
A relation in first normal form in which every non-key attribute is fully functionally dependent on the primary key
Term
Partial Functional Dependency
Definition
A functional dependency in which one or more non-key attributes are functionally dependent on part (but not all) of the primary key.
Term
Third Normal Form (3NF)
Definition
A relation that is in second normal form and has no transitive dependencies.
Term
Synonyms
Definition
Two (or more) attributes that have different names but the same meaning.
Term
Alias
Definition
An alternative name used for an attribute.
Term
Homonym
Definition
An attribute that may have more than one meaning
Term
Transitive dependency
Definition
A functional dependency between the primary key and one or more non-key attributes that are dependent on the primary key via another non-key attribute.
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