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Entity-Relationship Diagram (ERD)

entity-relationship diagram, ER-diagram, database ERD Entity-Relationship Diagram (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. Read more
entity-relationship diagram, ER-diagram, database ERD
"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
Chen's ERD, week key attribute, weak entity, relationship, multivalue attribute, key attribute, identifying relationship, entity, derived attribute, attribute, associative entity,

Use Case Diagrams technology with ConceptDraw PRO

Use case diagrams are used at the development of software and systems for definition of functional system requirements or system of systems. Use case diagram presents the consecution of object’s actions (user’s or system’s) which are executed for reaching the definite result. Read more