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23 Cards in this Set

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A functional dependency in which one or more non-key attributes are functionally dependent on part (but not all) of the primary key.
Partial Functional Dependency
The process of transforming the conceptual data model into a logical data model.
Logical DB Design
Model design that conforms to the data model for a class of database management systems.
Logical data model
The deliverable from logical database design
Normalized relations
Data duplication
Redundancy
Redundancy
Multiple value problems
Update anomalies
Insertion anomalies
Deletion anomalies
Problems with a "flat" database
Conceptual Data Model (E-R Diagram)
1) Represent Entities
2) Represent Relationships
3) Normalize the Relation
4) Merge the Relation
Logical Data model
4 Steps in Logical Design Process
Each entity in an E-R diagram is represented as a relation (a named two-dimensional table of data)
Represent Entities
Primary key of a relation is a foreign key of another (or)
Create a separate relation
Represent Relationships
Redesign for well structured relations that avoid anomalies
Normalize the relations
Delete redundant relations
Merge the relations
A named two-dimensional table of data. Consists of a finite set of named columns and an arbitrary number of unnamed rows.
Relation
Relation rows correspond with entity instances
Relation columns correspond with attributes
ER correspondence to Relations
An attribute (or combination of attributes) that uniquely identifies each row in a relation (guarantees all rows are unique)
Primary Key
Attribute that appears as a non-key attribute in one relation and as a primary key attribute (or part of a primary key) in another relation.
Foreign Key
The primary key attribute (or a component of primary key attribute) can never be null.
Entity Integrity
Either each foreign key value must match a primary key value in the other relation or the foreign key value must be null
Referential Integrity
Name of relation is name of Entity
Each simple attribute of entity becomes an attribute or column of relation
Identifier of entity becomes primary key of relation
Regular Entity
Include all simple attributes
Include the primary key of the owner relation as a foreign key attribute in this new relation
The primary key of this new relation is a combination of the primary key of the owner and the partial identifier of the entity
Mapping a weak entity
Entity whose existence depends on another entity
Weak entity
-Primary key on the mandatory side becomes a foreign key on the optional side
-Primary key on the one side becomes a foreign key on the many side
-Create a new relation with primary keys of the two entities as its primary key
One-to-one
One-to-many
Many-to-many
Two different names are used for the same attribute
Synonyms
One attribute name is used for two or more different attributes
Homonym