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"In software engineering, an entity–relationship model (ER model) is a data model for describing a database in an abstract way.Chen's notation for entity–relationship modeling uses rectangles to represent entity sets, and diamonds to represent relationships appropriate for first-class objects: they can have attributes and relationships of their own. If an entity set participates in a relationship set, they are connected with a line.
Attributes are drawn as ovals and are connected with a line to exactly one entity or relationship set." [Entity–relationship model. Wikipedia]
This sample Chen's ER-diagram illustrates the structure of a typical MMORP game.
"Massively multiplayer online role-playing game (MMORPG) mixes the genres of role-playing video games and Massively multiplayer online games, possibly in the form of web browser-based games, in which a very large number of players interact with one another within a virtual world.
As in all RPGs, players assume the role of a character (often in a fantasy world or science-fiction world) and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player online RPGs by the number of players, and by the game's persistent world (usually hosted by the game's publisher), which continues to exist and evolve while the player is offline and away from the game." [Massively multiplayer online role-playing game. Wikipedia]
This ERD example was redrawn using the ConceptDraw PRO diagramming and vector drawing software from the Wikipedia file: ER Diagram MMORPG.png. [en.wikipedia.org/ wiki/ File:ER_ Diagram_ MMORPG.png]
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. [creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
This Chen's ERD example is included in the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park.
Chen's ERD
Chen's ERD, weak key attribute, weak entity, relationship, multivalue attribute, key attribute, identifying relationship, entity, derived attribute, attribute,

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entity-relationship diagram, ER-diagram, database ERD Entity-Relationship Diagram (ERD)

entity-relationship diagram, ER-diagram, database ERD
Entity-Relationship Diagram (ERD) solution extends ConceptDraw PRO software with templates, samples and libraries of vector stencils from drawing the ER-diagrams by Chen's and crow’s foot notations.
"Crow's Foot notation is used in Barker's Notation, SSADM and Information Engineering. Crow's Foot diagrams represent entities as boxes, and relationships as lines between the boxes. Different shapes at the ends of these lines represent the cardinality of the relationship." [Entity–relationship model. Wikipedia]
The vector stencils library ERD, crow's foot notation contains 17 symbols for creating the ER-diagrams using the ConceptDraw PRO diagramming nd vector drawing software.
The example"Design elements - ERD solution (crow's foot notation)" is included in the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park.
Crow's foot ERD
Crow's foot ERD, entity,
HelpDesk

How to Create an Entity-Relationship Diagram Using ConceptDraw Solution Park

An entity-relationship diagram (ERD)is used in a database modeling process. ERD diagram shows a graphical representation of objects or concepts within an information system and their relationships.The ability to  describe a database using the Entity-Relationship model is delivered by the ConceptDraw ERD solution.

entity-relationship diagram, ER-diagram, database ERD Entity-Relationship Diagram (ERD)

entity-relationship diagram, ER-diagram, database ERD
An Entity-Relationship Diagram (ERD) is a visual presentation of entities and relationships. That type of diagrams is often used in the semi-structured or unstructured data in databases and information systems. At first glance ERD is similar to a flowch