Structured entity relationship model: Difference between revisions

Revision as of 10:10, 20 February 2009

Revision as of 21:30, 27 May 2009

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{{Orphan|date=February 2009}}

The '''SERM''' (Structured Entity Relationship Model) is an amplification of the [[Entity-relationship model|ERM]] which is commonly used for [[Data modeling|data modeling]]. It was first proposed from Prof. Dr. Sinz in 1989. The SERM is commonly used in the [[SAP AG|SAP]]-world for the [[Data modeling|data modeling]].

==Aims==

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[[Image:SERM-Symbols.JPG|600px|]]

==SERM-Example==

[[Image:SERM-example.JPG]]

* [[Customer|Customer]] and article are independent entities

* Every order is referred to one customer. Orders without [[Customer|customerscustomer]]s are illegal (order is an ER Type). [[Customer|Customers]]s without any orders are legal because they are independent Entities.

* To every order there is belonging at least one order item.

* Every order item is related to exactly one order.

* Every invoice is referred to one [[Customer|customer]], as well. Invoices without [[Customer|customerscustomer]]s are illegal. [[Customer|Customers]]s without any invoice are legal.

* To every invoice there is belonging at least one invoice line item.

* Every invoice line item is related to exactly order item. An order item could be calculated or not.

* SERM is already in the [[Third normal form|third normal form]]

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[[Category:Data modeling]]

[[Category:Diagrams]]

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