An entity relationship diagram (ERD) is a graph that represents relationships among people, concepts, events, etc. The picture above shows the primary symbols, entities, attributes, and their relationships, and how they would be used. There are two types of ERD notations, Chen and Crow’s Foot. The difference between the two is Crow’s Foot uses only lines with symbols at the end; but Chen notation uses diamonds and connects lines with symbols to describe relationships and something we call cardinality. Cardinality shows the numerical relationship between entities. In the picture below, I have included the different kinds of cardinality and what they mean.
Links to images used: https://www.learncomputerscienceonline.com/entity-relationship-diagram/
https://www.lucidchart.com/pages/ER-diagram-symbols-and-meaning
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