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I was interested in storing the history of properties which contains two entites - properties and owners. Right now I am not sure what approach to take and needed some help. I was thinking of creating an associative entity and so this would have its identity a combination of property and owner but the textbook comes up with this solution instead:

Solution

What's the difference between the solution above and an associative entity?

Clément Prévost
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MAD_DOG
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  • Please add more context to your question. Are you trying to create an UML diagram? For what reason? Generating SQL code, creating object oriented classes? Communicating your solution to other developers? – Clément Prévost Sep 09 '18 at 14:17
  • I'm creating an ER diagram as an exercise – MAD_DOG Sep 09 '18 at 14:26
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    Please [use text, not images/links, for text--including tables & ERDs](https://meta.stackoverflow.com/q/285551/3404097). Paraphrase or quote from other text. Give just what you need & relate it to your problem. Use images only for what cannot be expressed as text or to augment text. Images cannot be searched for or cut & pasted. Include a legend/key & explanation with an image. – philipxy Jan 27 '20 at 09:43

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The owns table in the given solution would be called an associative entity set in the network data model. This data model supports only one-to-one and one-to-many binary relationships, and resolves many-to-many binary relationships as well as ternary and higher relationships into an associative entity set with binary one-to-many relationships.

However, in the entity-relationship model, the owns table represents a many-to-many relationship relation. The ER model directly supports many-to-many binary relationships as well as ternary and higher relationships, and uses "associative entities" to refer only to relationships which are the subjects of other relationships.

reaanb
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