"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.
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.
Entity Relationship Diagram - ERD - Software for Design Crows Foot ER Diagrams
Crow's Foot notation was proposed by Gordon Everest. According to this notation, the entity is represented by rectangle, relation is depicted by line which ties two entities involved in a relationship. Entity-relationship diagrams based on both Chen's and Crow's Foot notations, can be easily drawn using the ConceptDraw PRO ERD diagrams software tools for design element Crow's Foot and Chen from Entity-Relationship Diagram (ERD) solution.Basic Flowchart Symbols and Meaning
Flowchart Symbols and Meaning - Provides a visual representation of basic flowchart symbols and their proposed use in professional workflow diagram, standard process flow diagram and communicating the structure of a well-developed web site, as well as their correlation in developing on-line instructional projects. See flowchart's symbols by specifics of process flow diagram symbols and workflow diagram symbols.Create Floor Plans Easily with ConceptDraw PRO
There are two basic ways of creating a floor plan: hiring an interior designer or designing on one’s own. Professional help can be quite expensive, and the result may not always be worth the money. Let’s take a look at what skills are needed to create the interior design on your own.Primarily, this basic knowledge of the composition rules. It helps to compose, to place the shapes and volume of the interior, to achieve balance in the room between the free space and objects. This might help to compose correctly, to place the shapes and the volumes in the interior, to achieve balance between free space and furniture in the room.
Basic color theory. There are strictly defined rules and laws, which are used to select a fitting color combinations to create a harmonious interior.
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