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subtype
a subgrouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other subgroupings
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supertype
a generic entity type that has a relationship with one or more subtype
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attribute inheritance
a property by which subtype entities inherit values of all attributes and instances of all relationships of the supertype
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generalization
the process of defining a more general entity type from a set of more specialized entity types
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specialization
the process of defining one or more subtypes of the supertype and forming supertype/subtype relationships
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completeness constraint
a type of contraint that addresses the question whether an instance of a supertype must also be a member of at least one subtype
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total specialization rule
specifies that each entity instance of the supertype must be a member of some subtype in the relationship
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partial specialization rule
specifies that an entity instance of the supertype is allowed not to belong to any subtype
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disjointness constaint
a constraint that addresses the question whether an instance of a supertype may simultaneously be a member of two(or more subtypes)
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disjoint rule
a rule that specifies that an instance of a supertype may not simultaneously be a member of two(or more) subtypes
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overlap rule
a rule that specifies that an instance of a supertype may simultaneously be a member of a member of two(or more) subtypes
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subtype discriminator
an attribute of the supertype whose values determine the target subtype or subtypes
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-supertype/subtype hierarchy
-a hierarchical arrangement of supertypes and subtypes, where each subtype has only one supertype
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entity cluster
a set of one or more entity types and associated relationships grouped into a single abstract entity type
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-universal data model
-a generic or template data model that can be reused as a starting point for a data modeling project
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business rules
statements that define or constrain some aspect of the business
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derivation
a statement derived from other knowledge in the business
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structural assertion
a statement that expresses some aspect of the static structure of the organization
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action assertion
a statement of a constraint or control on the actions of the organization
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derived fact
a fact that is derived from business rules using an algorithm or inference
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anchor object
a business rule(a fact) on which actions are limited
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action
an operation, such as create, delete, update, or read, which may be performed on data objects
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corresponding object
a business rule(a fact) that influences the ability to perform an action on another business rule
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relation
a named two-dimensional table of data
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primary key
an attribute(or combination of attributes) that uniquely identifies each row in a relation
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composite key
a primary key that consists of more than one attribute
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foreign key
an attribute in a relation that serves as the primary key of another relation in the same database
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null
a value that may be assigned to an attribute when no other value applies or when the applicable valus is unknown
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entity integrity rule
no primary ke attribute(or component of a composite primary key) may be null
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referential integrity constraint
a rule that states that either foreign key value must match a primary key value in another relation or the foreign key value must be null
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well-structured relation
a relation that contains minimal redundancy and allows users to insert, modify, and delete the rows in a table without errors or inconsistencies
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anomaly
an error or inconsistency that may result when a user attempts to update a table that contains redundant date. three types of anomalies are insertion, deletion, and modification
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surrogate primary key
a serial number or other system assigned primary key for a relation
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recursive foreign key
a foriegn key in a relation that references the primary key values of that same relation
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normalization
the process of decomposing relations with anomalies to produce smaller, well- structured relations
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normal form
a state of a relation that results from applying simple rules regarding functional dependencies for relationships between attributes to that relation
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functional dependency
a constraint between two attributes in which the value of one attributes is determined by the value of another attribute
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determinant
the attribute on the left-hand side of the arrow in a functional dependency
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candidate key
an attribute, or combination of attributes, that uniquely identifies a row in a relation
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first normal form(1NF)
a relation that has a primary key and in which there are no repeating groups
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second normal form(2NF)
a relation in first normal form in which every nonkey attribute is fully functionally dependent on the primary key
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partial functional dependency
a functional dependency in which one or more nonkey attributes aare functionally dependent on part(but not all) of the primary key
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third normal form(3NF)
a relation that is in second normal form and has no transitive dependencies
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transitive dependency
a functional dependency between two(or more) nonkey attributes
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transforming EER diagrams to relations
7 mapping relationship
- (1)-Mapping Regular Entities to Relations
- (2)-Mapping Binary Relationships
- -(One-to-Many, Many-to-Many, One-to-one)
- (3)-Mapping Weak Entities
- (4)-Mapping Associative Entities
- (5)-Mapping Unary Relationships
- (6)-Mapping Ternary (and n-ary) Relationships
- (7)-Mapping Supertype/Subtype Relationships
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3 classification of business rules
- Derivation
- Structural assertion
- Action assertion
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