An entity relationship diagram, also known as an entity relationship model, is a graphical representation that depicts relationships among people, objects, places, concepts or evetns within an information technology system.
ERD는 IT 내에서 사람, 객체, 공간, 개념, 사건 사이의 관계를 그리는 그래픽적 표현이다.
An ERD uses data modeling techniques that can help define business processes and serve as the foundation for a relational database.
A physical data model, which provides the blueprint for a physical manifestation.
물리적 데이터 모델은 흐름의 블루 프린트를 제공한다.
물리적 데이터 모델은 논리적 데이터 모델에 근간을 둔다
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A one-to-one relationship (1:1). For example, if each customer in a database is associated with one mailing address.
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A one-to-many relationship (1:M). For example, a single customer might place an order for multiple products. The customer is associated with multiple entities, but all those entities have a single connetion back to the same customer.
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A many-to-many relationship (M:N). For example, at a company where all cal center agents work with multiple custoemrs, each agent is associated with multiple customers, and multiple custoemrs might also be associated with multiple agents.
