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32 Cards in this Set
- Front
- Back
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Entity-relationship model
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A logical representation of the data for an organization or for a business area, using entities for categories of data and relationships for associations between entities.
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Entity-relationship diagram
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A graphical representation of an entity-relationship model.
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Business rule
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A statement that defines or constrains some aspect of the business. It is intended to assert business structure or to control or influence the behavior of the business.
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Term
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A word or phrase that has a specific meaning for the business.
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Fact
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An association between two or more terms.
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Entity
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A person, a place, an object, an event, or a concept in the user environment about which the organization wishes to maintain data.
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Entity type
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A collection of entities that share common properties or characteristics.
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Entity instance
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A single occurrence of an entity type.
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Strong entity type
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An entity that exists independently of other entity types.
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Weak entity type
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An entity type whose existence depends on some other entity type.
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Identifying owner
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The entity type on which the weak entity type depends.
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Identifying relationship
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The relationship between a weak entity type and its owner.
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Attribute
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A property or characteristic of an entity or relationship type that is of interest to the organization.
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Required attribute
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An attribute that must have a value for every entity (or relationship) instance with which it is associated.
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Optional attribute
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An attribute that may not have a value for every entity (or relationship) instance with which it is associated.
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Composite attribute
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An attribute that has meaningful component parts (attributes).
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Simple (or atomic) attribute
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An attribute that cannot be broken down into smaller components that are meaningful to the organization
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Multivalued attribute
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An attribute that may take on more than one value for a given entity(or relationship) instance.
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Derived attribute
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An attribute whose values can be calculated from related attribute values.
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Identifier
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An attribute (or combination of attributes) whose value distinguishes instances of an entity type.
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Composite identifier
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An identifier that consists of a composite attribute
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Relationship type
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A meaningful association between (or among) entity types.
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Relationship instance
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An association between (or among)entity instances where each relationship instance associates exactly one entity instance from each participating entity type
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Associative entity
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An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances.
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Degree
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The number of entity types that participate in a relationship.
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Unary relationship
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A relationship between instances of a single entity type.
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Binary relationship
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A relationship between the instances of two entity types
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Ternary relationship
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A simultaneous relationship among the instances of three entity types.
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Cardinality constraint
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A rule that specifies the number of instances of one entity that can(or must) be associated with each instance of another entity
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Minimum cardinality
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The minimum number of instances of one entity that may be associated with each instance of another entity.
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Maximum cardinality
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The maximum number of instances of one entity that may be associated with each instance of another entity.
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Time stamp
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A time value that is associated with a data value, often indicating when some event occurred that affected the data value.
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