What is an ERD. Define the ERD related terms, including entities, attributes, cardinalities and relationships

    Definition:

An entity-relationship diagram is a kind of flowchart that shows how entities such as people, things, and concepts are related to each other in a system. Also known as ERD model, it uses a predefined set of symbols such as rectangles, diamonds, ellipses, and connecting lines to represent the interconnectivity of entities, relationships, and their attributes. They reflect grammatical relationships,  similar with nouns as entities and verbs as relations (Moqups, 2022).

   Components:

The ERD diagram model it uses a standardized type of diagram with symbols specific to concepts assign to them.

• Entities: they can be represented by persons, objects, concept and which can have data stored about them. Entities can be classified as weak, strong and associative. Entities use the concept of primary keys and candidate. 
• Relationships: display how entities are associated or interact between each other. Usually are represented on the lines that connect the objects (Biscobing, 2019).
• Attributes: they represent the characteristics of  an entity and can be simple, derived and composite. It is possible for an object to have multiple attributes .
• Cardinality: represents the numerical relationship present between entities. They can be : one to one, one to many, many to one and many to many (Neha, 2021).

   Application:

The start to creates an ERD is to identify the purpose that it will have. Next step will involve the identification of all entities involved and their representation on graphic. Furthermore, the relationships between entities will be identified and their numerical value and lastly the key attributes of the entities (Lucidchart, 2022). 

   

     

References

Biscobing, 2019. What is Entity Relationship Diagram (ERD)? - Definition from WhatIs.com. [online] SearchDataManagement. Available at: <https://www.techtarget.com/searchdatamanagement/definition/entity-relationship-diagram-ERD> [Accessed 7 September 2022].

Lucidchart, 2022. What is an Entity Relationship Diagram (ERD)?. [online] Lucidchart. Available at: <https://www.lucidchart.com/pages/er-diagrams> [Accessed 7 September 2022].

Moqups, 2022. ERD Templates | ER Diagram Examples | Moqups. [online] Moqups.com. Available at: <https://moqups.com/templates/diagrams-flowcharts/erd/#:~:text=ER%20diagrams%20or%20ERD's%20are,entities%2C%20attributes%2C%20and%20relationships.> [Accessed 7 September 2022].

Neha, 2021. What is Entity Relationship Diagram (ERD)? Uses, Components, Symbols & Examples - Binary Terms. [online] Binary Terms. Available at: <https://binaryterms.com/entity-relationship-diagram.html> [Accessed 7 September 2022].