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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.
"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.
Chen's ERD
Chen's ERD, week key attribute, weak entity, relationship, multivalue attribute, key attribute, identifying relationship, entity, derived attribute, attribute, associative entity,
HelpDesk

How to Create an ERD Diagram

ERD (entity relationship diagram) is used to show the logical structure of databases. It represents the interrelationships between components of database (entities). Entity relationship diagrams are a widely used in software engineering. Using ERD software engineers can control the every aspect of database development. ER diagram can be used as guide for testing and communicating before the release of software product. ERD displays data as entities that are connected with connections that show the relationships between entities. There is some ERD notations used by data bases developers for representing the relationships between the data objects. ConceptDraw PRO and its ERD solution allow you to build ERD diagram of any notation.
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.
Entity
Entity, entity,
Weak entity
Weak entity, weak entity,
Relationship
Relationship, relationship,
Identifying Relationship
Identifying Relationship, identifying relationship,
Associative Entity
Associative Entity, associative entity,
Participation
Participation,
Optional participation
Optional participation,
Recursive Relationship
Recursive Relationship,
Attribute
Attribute, attribute,
Key attribute
Key attribute, key attribute,
Weak key attribute
Weak key attribute, weak key attribute,
Derived attribute
Derived attribute, derived attribute,
Multivalue attribute
Multivalue attribute, multivalue attribute,