# Design elements - ER diagram (Chen notation)

## Design elements - ER diagram (Chen notation)

"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.
Cardinality constraints are expressed as follows:
- a double line indicates a participation constraint, totality or surjectivity: all entities in the entity set must participate in at least one relationship in the relationship set;
- an arrow from entity set to relationship set indicates a key constraint, i.e. injectivity: each entity of the entity set can participate in at most one relationship in the relationship set;
- a thick line indicates both, i.e. bijectivity: each entity in the entity set is involved in exactly one relationship.
- an underlined name of an attribute indicates that it is a key: two different entities or relationships with this attribute always have different values for this attribute.
Attributes are often omitted as they can clutter up a diagram; other diagram techniques often list entity attributes within the rectangles drawn for entity sets." [Entity–relationship model. Wikipedia]
The vector stencils library ERD, Chen's notation contains 13 symbols for drawing entity-relatinship diagrams using the ConceptDraw PRO diagramming and vector drawing software.
The example "Design elements - ER diagram (Chen notation)" is included in the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park. Read more
Chen's ERD
Used Solutions

## Entity Relationship Diagram Symbols

The semantic modeling method nowadays is successfully applied in database structure design. It is effective method of modeling the data structures, which is based on the meaning of these data. As a tool of semantic modeling, there are used different types of Entity-Relationship Diagrams. Entity Relationship Diagram (ERD) is applied to visually and clearly represent a structure of a business database. The main components of ERDs are: entity, relation and attributes. An entity is a class of similar objects in the model, each entity is depicted in the form of rectangle and has the name expressed by a noun. Relation is shown in the form of non-directional line that connects two entities. There are several notation styles used for ERDs: information engineering style, Chen style, Bachman style, Martin Style. The Entity Relationship Diagram symbols used for professional ERD drawing are predesigned by professionals and collected in the libraries of the Entity-Relationship Diagram (ERD) solution for ConceptDraw PRO software. Read more

## ERD Symbols and Meanings

Entity Relationship Diagram (ERD) is a popular software engineering tool for database modeling and illustration the logical structure of databases, which uses one of two notations - Chen's or Crow’s Foot. Crow's foot notation is effective when used in software engineering, information engineering, structured systems analysis and design. Each of these notations applies its own set of ERD symbols. Crow's foot diagrams use boxes to represent entities and lines between these boxes to show relationships. Varied shapes at the ends of lines depict the cardinality of a given relationship. Chen's ERD notation is more detailed way to represent entities and relationships. ConceptDraw PRO application enhanced with all-inclusive Entity-Relationship Diagram (ERD) solution allows design professional ER diagrams with Chen's or Crow’s Foot notation on your choice. It contains the full set of ready-to-use standardized ERD symbols and meanings helpful for quickly drawing, collection of predesigned ERD samples, examples and templates. ConceptDraw Pro is a great alternative to Visio for Mac users as it offers more features and can easily handle the most demanding professional needs. Read more

## Chen Notation

The Chen Notation solution extends ConceptDraw PRO v10 software with rich collection of ERD samples and selection of special Chen's notation icons for effective database design, data modeling, and visual representation of relationships between the entities on the ER diagrams designed with Chen notation. Read more

## Entity Relationship Software

Entity Relationship Diagram (ERD) is a leading data modeling tool that is used to illustrate the logical structure of database, helps to organize and represent your project's data in terms of entities, attributes and relationships. To describe the database structure usually is used the ERD Chen's or Crow's Foot notation. Chen's notation supposes the representation of entities by rectangles with the entities names inside, relationships by diamonds and attributes by ovals connected with a line to exactly one entity. In Crow's Foot notation the boxes are used to depict the entities and their attributes, the lines between them - to depict relationships. ConceptDraw PRO software extended with Entity-Relationship Diagram (ERD) Solution is convenient and useful for designing the ER Diagrams, and supports the use of Chen's or Crow’s Foot notation according to your needs and desires. The ERD diagrams produced with ConceptDraw PRO Entity Relationship Diagram software can be successfully used in whitepapers, presentations, posters, datasheets, technical materials, etc. Read more

## ERD, Chen's notation - Vector stencils library

The vector stencils library "ERD, Chen's notation" contains 13 ERD elements.
Use it for drawing ER-diagrams using Chen's notation in the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park. Read more
Entity
Weak entity
Relationship
Identifying Relationship
Associative Entity
Participation
Optional participation
Recursive Relationship
Attribute
Key attribute
Weak key attribute
Derived attribute
Multivalue attribute
Used Solutions

## Notation & Symbols for ERD

The ER diagram is constructed from the specific ERD graphic elements. There are used 2 types of ERD notations: Chen and Crow's Foot. A complete set of work flow shapes, notation & symbols for ERD, entity relationship stencils, included in Entity-Relationship Diagram (ERD) solution for ConceptDraw PRO software, makes drawing diagrams based on ERD notation as smooth as possible. Read more

## ConceptDraw PRO ER Diagram Tool

Entity-relationship model, also called ER-model, is the main tool of domain modeling on the stage of conceptual design. The modeling of domain data structures is based on the use of graphical tools - Entity-Relationship diagrams (ER-diagrams). The core concepts of ER-Diagram are entity, attribute and relationship. ER-diagram lets visually represent the entities, helps effectively document all properties of designed system and to detail the data storages. To represent the elements at ER-model are commonly used Chen’s notation and Crow’s foot notation, each has its pros and cons. The entity on ER-diagram is represented in the form of rectangle, which specifies its name. An attribute is a property of the entity and relationship is an interaction between the entities. The relationship between two entities is called binary, between more than two entities - ternary. Specific software, such as ConceptDraw PRO with Entity-Relationship Diagram (ERD) solution from ConceptDraw Solution Park is helpful for easy creation Entity-Relationship Diagrams. Read more

## ERD, Chen's notation - Vector stencils library

The vector stencils library "ERD, Chen's notation" contains 13 ERD elements.
Use it for drawing ER-diagrams using Chen's notation in the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park. Read more
Entity
Weak entity
Relationship
Identifying Relationship
Associative Entity
Participation
Optional participation
Recursive Relationship
Attribute
Key attribute
Weak key attribute
Derived attribute
Multivalue attribute
Used Solutions

## Anyone Have an ERD Symbols Quick Reference?

ERD drawing becomes easier with predesigned entity relationship symbols, work flow shapes, entity relationship stencils. All variety of ERD symbols you may need for ERDs design is packed into libraries and templates from Entity-Relationship Diagram (ERD) Solution for ConceptDraw PRO diagramming and vector drawing software. But anyone have an ERD symbols quick reference? Detailed reference information for them is represented at the tables. Read more

## Chen notation ERD of MMORPG

"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 Chen's ERD example is included in the Chen Notation solution from the Software Development area of ConceptDraw Solution Park. Read more
ER-diagram
Used Solutions

## ERD, Chen's notation - Vector stencils library

The vector stencils library "ERD, Chen's notation" contains 13 ERD elements.
Use it for drawing ER-diagrams using Chen's notation in the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park. Read more
Entity
Weak entity
Relationship
Identifying Relationship
Associative Entity
Participation
Optional participation
Recursive Relationship
Attribute
Key attribute
Weak key attribute
Derived attribute
Multivalue attribute
Used Solutions

## ERD Symbols and Meanings

Entity Relationship Diagram (ERD) is a popular software engineering tool for database modeling and illustration the logical structure of databases, which uses one of two notations - Chen's or Crow’s Foot. Crow's foot notation is effective when used in software engineering, information engineering, structured systems analysis and design. Each of these notations applies its own set of ERD symbols. Crow's foot diagrams use boxes to represent entities and lines between these boxes to show relationships. Varied shapes at the ends of lines depict the cardinality of a given relationship. Chen's ERD notation is more detailed way to represent entities and relationships. ConceptDraw PRO application enhanced with all-inclusive Entity-Relationship Diagram (ERD) solution allows design professional ER diagrams with Chen's or Crow’s Foot notation on your choice. It contains the full set of ready-to-use standardized ERD symbols and meanings helpful for quickly drawing, collection of predesigned ERD samples, examples and templates. ConceptDraw Pro is a great alternative to Visio for Mac users as it offers more features and can easily handle the most demanding professional needs. Read more

## ERD, Chen's notation - Vector stencils library

The vector stencils library "ERD, Chen's notation" contains 13 ERD elements.
Use it for drawing ER-diagrams using Chen's notation in the ConceptDraw PRO diagramming and vector drawing software extended with the Entity-Relationship Diagram (ERD) solution from the Software Development area of ConceptDraw Solution Park. Read more
Entity
Weak entity
Relationship
Identifying Relationship
Associative Entity
Participation
Optional participation
Recursive Relationship
Attribute
Key attribute
Weak key attribute
Derived attribute
Multivalue attribute
Used Solutions

## Design Element: Chen for Entity Relationship Diagram - ERD

Entity-Relationship Diagrams (ERDs) were developed and introduced as a convenient and visual tool for the data modeling, they are the perfect way for easy determining data and also relationships between them. The first standard notation for ERD was proposed by Chen. Chen's notation is very rich on the data modeling tools and standard notation symbols and elements for drawing easy understandable Entity-relationship diagrams, Attribute diagrams, Decomposition charts, which are especially popular for designing relational databases. The entity is the main term, it is a set of instances abstract or real objects with common characteristics or attributes. Any system's object is represented by one uniquely identified entity, relationships describe the links between the entities. ConceptDraw PRO diagramming software, which includes the Entity-Relationship Diagram (ERD) solution, offers all needed tools for professional drawing ER diagrams. Specially developed vector ERD design elements according to Chen and Crow's Foot notations are indispensible for professional ERDs design. Read more