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Topic: Entity relationship diagram

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	Entity-relationship model -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-06)
		Relationships can be thought of (again, roughly) as (A word that serves as the predicate of a sentence) verbs.
		A weak entity is an entity that can't be uniquely identified by its own attributes alone, and therefore must use as its primary key both its own attributes and the primary key of an entity it is related to.
		A weak entity set is indicated by a bold rectangle (the entity) connected by a bold arrow to a bold diamond (the relationship).
	www.absoluteastronomy.com /encyclopedia/e/en/entity-relationship_model.htm (1069 words)

	Data Modeling: Entity-Relationship Model
		Entities are classified as independent or dependent (in some methodologies, the terms used are strong and weak, respectively).
		Subtypes entities are used in generalization hierarchies to represent a subset of instances of their parent entity, called the supertype, but which have attributes or relationships that apply only to the subset.
		The entity from which a relationship originates is the parent entity; the entity where the relationship terminates is the child entity.
	www.utexas.edu /its/windows/database/datamodeling/dm/erintro.html (1648 words)

	Entity Relationship Diagram
		Entity relationship diagrams are not to be confused with data flow diagrams.
		Entities are labelled by nouns whereas relationships are labelled using verbs.
		Entities have (of course) one key, and relationships have two keys, one key from each entity involved in the relationship.
	www.cs.ntu.edu.au /homepages/paule/sit-101/slidesnode158.html (599 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		A relationship is represented by a diamond shape containing a verb that describes the relationship.
		The diamond is connected to each entity involved in the relationship by a line with one or two arrows pointing to the entity.
		A single arrow indicates that the relationship exists for each individual entity; a double arrow indicates that one or more entities may be involved in the relationship.
	www.ucop.edu /pathways/plan/erdnote.html (342 words)

	Data Modeling: Refining The Entity-Relationship Diagram
		Complex relationships are classified as ternary, an association among three entities, or n-ary, an association among more than three, where n is the number of entities involved.
		The complex relationship replaced by an association entity and the original entities are related to this new entity.
		A redundant relationship is a relationship between two entities that is equivalent in meaning to another relationship between those same two entities that may pass through an intermediate entity.
	www.utexas.edu /its/windows/database/datamodeling/dm/refining.html (516 words)

	Entity Relationship Diagram Quick Reference
		Entity Relationship Diagramming is used to create a data model for the business or system.
		Initially, a version of the ERD may be used to elicit and document the client user requirements as a Conceptual Data Model.
		The ERD may be then refined to produce a Logical Data Model by data modelers to complete it and eliminate anomalies and redundancies (see Normalization).
	www.infoarchgroup.com /qrerd.htm (224 words)

	CRDSS/Hydrobase Comparison Table (Site not responding. Last check: 2007-11-06)
		Entities are usually nouns in the form of a person, place or thing, or event of informational interest.
		The entity-relationship approach's primary area of emphasis is the diagramming of the associations between entities.
		Once the entities and their relationships have been identified the attributes for each entity are defined.
	cdss.state.co.us /manuals/db/entity.html (379 words)

	DeZign for databases - entity relationship diagram, visual database design (Site not responding. Last check: 2007-11-06)
		Entity symbols are used to define database table structures, including details about columns (attributes), primary keys, null, unique, foreign keys, domains, check constraints,....
		Relationships are drawn between entities and can include a name, abbreviation, description and the cardinalities (zero, one, many,...).
		A modification to a property of a relationship or to a primary key will automatically affect foreign keys and will be visible when you're designing in a more physical displaymode.
	www.heraut.demon.nl /dezign/factsheet.html (889 words)

	Entity-Relationship Diagram
		A diagram that shows how a number of pieces or sets of data are related.
		Each arrow between data items may be labeled to help clarify the relationship between the two items on either end of the arrow.
		The Entity-Relationship Diagram can be used in database design, where it shows how data elements are related.
	syque.com /improvement/Entity-RelationshipDiagram.htm (126 words)

	Database Design Issues (Site not responding. Last check: 2007-11-06)
		An Entity Relationship Diagram (ERD) is a graphical representation of the relationships among tables in a database
		A one-to-many relationship may be represented by a line with a dot on the 'many' end; sometimes the line will be annotated with an 'N' or, in SQL Server, with an infinity symbol on the 'many' end
		A dependent relationship is one where the PK of a dependent table is also a FK; typically the dependent table box is drawn with rounded corners
	www.frick-cpa.com /ss7/Theory_ERD.asp (558 words)

	Checklist for Entity Relationship Diagram (Site not responding. Last check: 2007-11-06)
		The following checklist can be used to check your ERD for potential error.
		See if there is any Attribute that is confused with an Entity.
		o Scan the ERD for Many-Many relationship; a redesign may be in order depends on the nature of the relationship (break the relationship using an intermediate entity or turn it into a Fan pattern).
	www.geocities.com /limjetwee/ERD_Checklist.html (196 words)

	Entity Relationship Diagrams
		Entities are the "things" about which we seek information.
		Relationships provide the structure needed to draw information from multiple entities.
		Define Relationships: these are usually verbs used in descriptions of the system or in discussion of the business rules (entity ______ entity); identified in the narrative (see
	www.umsl.edu /~sauter/analysis/er/er_intro.html (456 words)

	System Architect - Entity-Relationship Diagram
		An example of the definition window for entities can be found at the end of this section.
		When all entity properties and associated attribute properties are completed, press the OK button on the Definition window to return to the diagram.
		The name of symbols on a diagram serves as the key data, and cannot be duplicated for any given diagram.
	www.uark.edu /depts/cisqinfo/sa/erd.html (1678 words)

	ERD - Emergency Repair Disk, Entity-Relationship Diagram
		traversal after arrival, return, or departure (The ERD option differs from the A option only when there are more than two anchors of the hyperlink).
		This is a diagram which models the information that must be "remembered" and therefore "stored" by a software system over a period of time.
		An entity relationship diagram is used to design a RDB (relational database) and to document this design.
	www.auditmypc.com /acronym/ERD.asp (200 words)

	What is entity-relationship diagram? - A Word Definition From the Webopedia Computer Dictionary
		(n.) Also called an entity-relationship model, a graphical representation of entities and their relationships to each other, typically used in computing in regard to the organization of data within databases or information systems.
		An entity is a piece of data—an object or concept about which data is stored.
		A relationship is how the data is shared between entities.
	www.webopedia.com /TERM/E/entity_relationship_diagram.html (201 words)

	Adding Sub-Types into an Entity-Relationship Diagram (Site not responding. Last check: 2007-11-06)
		You need to identify the nature of this subtype relationship in advance, before incorporating the sub-types on the diagram.
		On the exclusiveness dimension, the sub-types can be exclusive or inclusive, where the former indicates that an instance of the entity can belong to at most onel subtype, whereas the latter indicates possible membership in more than one sub-types.
		In this example, the STUDENT entity will be partitioned into graduate and undergraduate students, which represents covering and exclusive relationships in the sub-type set.
	www.uwm.edu /~derek/course/Tools/CASE/keyclass.html (317 words)

	EPA > STORET > Entity Relationship Diagram (Site not responding. Last check: 2007-11-06)
		This graphical representation of the STORET Entity Relationship Diagram (ERD) is provided as an aid to understanding the complexity of the STORET v2.0 database, and to assist programmers who may wish to write queries directly against the database tables or views.
		The file "ERD.pdf" is a large format version suitable for printing on a 36'' or larger plotter.
		Further information about printing the ERD is available on the STORET FAQ.
	www.epa.gov /storet/erd_20.html (224 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		The entity relationship diagram shows the entity types and relationships between these entity types for the area defined in the system scope.
		For complex situations, an Entity Type Decomposition Diagram may also be made.
		For complex situations, an entity life cycle subtype hierarchy may also be included.
	sysdev.ucdavis.edu /webadm/document/td_attrib-deliver.htm (89 words)

	Entity-Relationship Diagram (Site not responding. Last check: 2007-11-06)
		Entity-Relationship diagrams (ERD) emerged in the 1970's from work by Dr. Peter Chen and others.
		They were looking for means to simplify the representation of large and complex data storage concepts.
		Since ERD relationships are between entities, the ERD is not capable of expressing intra-entity, inter- attribute relationships - i.e., within one entity.
	www.aisintl.com /case/olais/pb96/er_mode2.htm (70 words)

	The Entity Relationship Diagram (Site not responding. Last check: 2007-11-06)
		In the text, lines may be directed (have an arrow on the end) to signify mapping cardinalities for relationship sets.
		They express the number of entities to which an entity can be associated via a relationship.
		Think of the arrow head as pointing to the entity that ``one'' refers to.
	www.cs.sfu.ca /CC/354/zaiane/material/notes/Chapter2/node8.html (123 words)

	Entity relationship diagram
		I need help in designing a database for my company, in terms of drawing the layout in ER diagram.
		There is this entity that i want to model, one that contains recorded information on temperature, sound and light value for a particular room,(and which is in a particular building).
		If anyone specializes in drawing ER diagrams for databases, if you can advise me in designing a database for this, i'd be very happy.
	www.seo-guy.com /forum/newpostinthread6530.html (203 words)

	dBforums - Correct Entity Relationship Diagram Notation.
		What is the correct Entity Relationship Diagram Notation or the most widely
		I have seen so many different notiations that I have becmoe a little confused.
		You may notice that IE relationship symbols are more clearly
	www.dbforums.com /t420745.html (265 words)

	Datanamic - Tools for Database Developers
		"DeZign for Databases" is a database development tool using an entity relationship diagram.
		It visually supports the lay out of the entities and relationships and automatically generates SQL-schemas for most leading databases.
		This new function automatically selects all children and grandchildren of an entity.
	www.datanamic.com (533 words)

	dBforums - Entity Relationship Diagram
		I need to draw a single Entity Relationship Diagram (ERD) to represent the following situation, which is described by means of text and a relational data model.
		How do you start a diagram, do you follow the flow of the primary and foreign keys?
		I read that they should be expressed as verbs, why can't the primary keys be used in the diagram?
	www.dbforums.com /t985886.html (335 words)

	entity-relationship diagram (Site not responding. Last check: 2007-11-06)
		The model says that you divide your database in two logical parts, entities (e.g.
		Entity-relationship diagrams can be used to represent a model.
		Nearby terms: Enterprise Systems CONnectivity « EntireX « entity-relationship diagram « entity-relationship model » entropy » Entry Sequenced Data Set » enumerated type
	www.linuxguruz.com /foldoc/foldoc.php?entity-relationship+diagram (91 words)

	ipedia.com: Database Article (Site not responding. Last check: 2007-11-06)
		Thus, the tables are related by references, which can be viewed as a network structure.
		A particular subset of the network model, the hierarchical model, limits the relationships to a tree structure, instead of the more general directed graph structure implied by the full network model.
		relations of n-tuples (tables of rows) of data elements (or attributes or columns); each n-tuple (row) is a colection of data elements (attributes/columns) of the entity represented by that particular n-tuple (row);
	www.ipedia.com /database.html (1479 words)

	The Cadastral Entity Relationship Diagram (Site not responding. Last check: 2007-11-06)
		Click here to see page two of the cadastral entity relationship diagram.
		To learn how to read the diagram above, refer to the section on Understanding the Diagram Conventions.
		For definitions and descriptions of the entities and attributes shown in the diagram above, refer to the Directory of Entities and Attributes.
	www.fairview-industries.com /standardmodule/cad-erd.htm (73 words)

	The Entity-Relationship Model (Site not responding. Last check: 2007-11-06)
		Next: Entities and Entity Up: Table of Contents Previous: Table of Contents
		The E-R (entity-relationship) data model views the real world as a set of basic objects (entities) and relationships among these objects.
		It is intended primarily for the DB design process by allowing the specification of an enterprise scheme.
	www.cs.sfu.ca /CC/354/zaiane/material/notes/Chapter2/node1.html (76 words)

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