Structured entity relationship model

<h2 id="aims">Aims</h2>
<ol><li>structuring of large schemes</li>
<li>visualization of existence dependency</li>
<li>avoidance of inconsistencies</li>
<li>avoidance of unnecessary relationshiptypes</li></ol>
<h2 id="serm-symbols">SERM symbols</h2>

<h2 id="serm-example">SERM example</h2>

<ul><li>Customer and article are independent entities</li>
<li>Every order is referred to one customer. Orders without customers are illegal (order is an ER type). Customers without any orders are legal because they are independent Entities.</li>
<li>To every order there is belonging at least one order item.</li>
<li>Every order item is related to exactly one order.</li>
<li>Every invoice is referred to one customer, as well. Invoices without customers are illegal. Customers without any invoice are legal.</li>
<li>To every invoice there is belonging at least one invoice line item.</li>
<li>Every invoice line item is related to exactly order item. An order item could be calculated or not.</li>
<li>SERM is already in the <a href="/facts/Third_normal_form/44D2DWId">third normal form</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Michael Röthlin (2010). Management of Data Quality in Enterprise Resource Planning Systems. BoD – Books on Demand. pp. 118–. ISBN 978-3-89936-963-2. <a href="978-3-89936-963-2" target="_blank">978-3-89936-963-2</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Structured entity relationship model open-in-new

Structured entity relationship model