I am currently reading about entities and relations and I can't understand the difference between them? According to Wikipedia we have an example of a relation like in the pic:


This looks exactly like an entity set. What's the difference between an entity and a relation?

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    Maybe you mean, entity vs relationship? As in ER modeling? Both have associated relations/tables, types/classes and sets (of instances). – philipxy Jan 3 '16 at 1:29

"Entity" is a real world concept, such as "a person" in your example.

"Relation" is a set of tuples (records), each representing a model of an entity. In your example each tuple represents attributes of a single person, and their collection is a relation.

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  • I would also add that a Relation has a header. – Lennart Jun 9 '16 at 13:09

"She is my mother."

"She" and the implied "you" are the entities. "Mother" is the relationship.

"Sally Smith is my mother."

"Sally Smith" is a particular entity (a row in a table).

Or: how does this thing relate to that thing?

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  • The question seems to be about relations, not relationships. – ypercubeᵀᴹ Jan 7 '16 at 23:38

Relation is an instance ( a record) of an entity

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