Term
| Entity-relationship Model (E-R Model) |
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Definition
| 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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Term
| Entity-relationship Diagram (E-R Diagram, or ERD) |
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Definition
| A graphical representation of an entity-relationship model. |
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Term
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Definition
| 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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Definition
| 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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Definition
| A collection of entities that share common properties or characteristics. |
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Definition
| A single occurrence of an entity type. |
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Definition
| An entity that exists independently of other entity types. |
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Definition
| An entity type whose existence depends on some other entity type. |
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Definition
| The entity type on which the weak entity type depends. |
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Definition
| The relationship between a weak entity type and its owner. |
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Definition
| A property or characteristic of an entity or relationship type that is of interest to the organization |
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Term
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Definition
| An attribute that must have a value for every entity (or relationship) instance with which it is associated. |
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Definition
| An attribute that may not have a value for every entity (or relationship) instance with which it is associated. |
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Term
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Definition
| An attribute that has meaningful component parts (attributes). |
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Term
| Simple (or Atomic) Attribute |
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Definition
| An attributes that cannot be broken down into smaller components that are meaningful to the organization. |
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Term
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Definition
| An attribute that may take on more than one value for a given entity (or relationship) instance. |
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Definition
| An attribute whose values can be calculated from related attribute values. |
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Definition
| An attribute (or combination of attributes) whose value distinguishes instances of an entity type. |
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Definition
| An identifier that consists of a composite attribute. |
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Definition
| A meaningful association between (or among) entity types. |
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Definition
| 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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Definition
| 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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Definition
| The number of entity types that participate in the relationship. |
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Definition
| A relationship between instances of a single entity type. |
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Definition
| A relationship between the instance of two entity types. |
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Definition
| The simultaneous relationship among the instances of three entity types. |
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Definition
| 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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Definition
| The minimum number of instances of one entity that may be associated with each instance of another entity. |
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Definition
| The maximum number of instances of one entity that may be associated with each instance of another entity. |
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Term
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Definition
| 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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