Entity Relationship Diagram Flashcards, test questions and answers

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What is Entity Relationship Diagram?

An Entity Relationship Diagram (ERD) is a graphical representation of the logical relationships between entities in a system. It is used to analyze and model information systems, as well as design databases. ERDs are commonly used in software engineering and database design to visualize the structure of a system. ERDs have three main components: entities, relationships, and attributes. Entities represent items or objects in the system, such as customers or products. Relationships represent how two entities interact with each other; for example, a customer may place an order for product A from supplier B. Attributes are characteristics associated with particular entities; for example, a customer may have an age or address attribute associated with it. The diagram consists of boxes (entities) connected by lines (relationships). The direction of the arrow indicates the type of relationship between two entities: one-to-one (where one entity is related to one other entity), one-to-many (where one entity can be related to many other entities), or many-to-many (where multiple entities can be related to multiple other entities). ERDs also indicate cardinalitythe number of instances that can exist for each relationshipusing numbers on the arrows connecting two boxes. When creating an ERD, it’s important to consider all possible scenarios and use cases that could apply within your system so that you can accurately model its structure and create meaningful relationships between your data elements. Additionally, you should pay careful attention to naming conventions when creating your diagram so that it’s easy for others to understand what each element represents without having to refer back to your code or documentation repeatedly.