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There exist databases which support inheritance. E.g PostgresSQL, &nbsp;that would be a good idea. The other is using some OR Mapper frameworks like e.g Rails which have support for inheritance in their &quot;framework&quot;. <br />
<br />
Regards<br />
Friedrich
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Sorry for the follow-up. Of course one can use OO Databases which were especially build for persistence of OO Data. Some databases like Oracle claim to support that, I can not say how true that really is. <br />
<br />
There are quite a few OO Databases available<br />
<a href="http://www.versant.com/en_US/products/objectdatabase?gclid=CJOKkaTj-ZgCFcST3wod8SGslQ" rel="ugc">http://www.versant.com/en_US/products/objectdatabase?gclid=CJOKkaTj-ZgCFcST3wod8SGslQ</a><br />
<br />
or <a href="http://www.progress.com/objectstore/index.ssp" rel="ugc">http://www.progress.com/objectstore/index.ssp</a><br />
<br />
Regards<br />
Friedrich
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Hi Friedrich,<br />
I appreciate the input but the company runs on MSSQL so switching platforms isn't really feasible. We're building on .NET so there won't be any problem with handling the inheritance on the code side of things. &nbsp;I'm just trying to figure out the best way to structure the tables to represent the data relationships.
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You did not mention MSSQL anywhere. So you have to go the route of the OR Mappers. I bet that there is something for that in the .NET framework....
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Sorry for not mentioning MSSQL, I'm looking for more generic &quot;data architecture&quot; help than anything. You're right about the OR Mappers we're considering using one in a future version but for the time being we're still trying to work up the table architecture so that if we need to access the data by any other means, the database architecture will be relatively sound.<br />
<br />
Can you suggest anything from a database design standpoint as far as whether I should go with the current table structure or consolidate the 2 middle tables and &nbsp;make them self referencing?<br />
<br />
Thanks again for your input!
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Btw. A table per subclass is my preferred choice as it is flexible and it adheres to the D.R.Y principle.<br />
That being said, keep in mind that it can cause performance problems when you have a large amount of subclasses. The excessive joining required can make queries slow and ugly (but that's always an issue when designing your DB, How much does one normalize a particular concept?. 
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Thanks again for your help. It definitely got me pointed in the right direction.!
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<div class="content wysiwyg-content">
I'm trying to figure out the best way to construct database tables to support what are, programmatically speaking, derived classes.<br />
<br />
My base class will be &quot;Request&quot; <br />
<br />
&quot;OriginalRequest&quot; &amp;&nbsp;&quot;AmendedRequest&quot; both extend &quot;Request&quot;. <br />
<br />
&quot;OriginalRequest&quot; is a parent of &quot;AmendedRequest&quot; with a one-to-many relationship.<br />
<br />
&nbsp;In constructing the database tables, given that &quot;OriginalRequest&quot; &amp;&nbsp;&quot;AmendedRequest&quot; are only different by one attribute and their children are virtually identical, &nbsp;is it wise to build the tables as I have in the attached diagram, better to consolidate the requests and add fields to make it self-referencing to preserver the Original to Amended relationship or a different way all together?<br />
<br />
<br />
Thanks in advance for your time &amp;&nbsp;help.<br />
<br />
<br />
<a href="https://filedb.experts-exchange.com/incoming/2009/02_w09/110403/db.jpg" target="_blank" class="file-inline" title="Roughed out data model (51 KB)"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path d="M67.508 468.467c-58.005-58.013-58.016-151.92 0-209.943l225.011-225.04c44.643-44.645 117.279-44.645 161.92 0 44.743 44.749 44.753 117.186 0 161.944l-189.465 189.49c-31.41 31.413-82.518 31.412-113.926.001-31.479-31.482-31.49-82.453 0-113.944L311.51 110.491c4.687-4.687 12.286-4.687 16.972 0l16.967 16.971c4.685 4.686 4.685 12.283 0 16.969L184.983 304.917c-12.724 12.724-12.73 33.328 0 46.058 12.696 12.697 33.356 12.699 46.054-.001l189.465-189.489c25.987-25.989 25.994-68.06.001-94.056-25.931-25.934-68.119-25.932-94.049 0l-225.01 225.039c-39.249 39.252-39.258 102.795-.001 142.057 39.285 39.29 102.885 39.287 142.162-.028A739446.174 739446.174 0 0 1 439.497 238.49c4.686-4.687 12.282-4.684 16.969.004l16.967 16.971c4.685 4.686 4.689 12.279.004 16.965a755654.128 755654.128 0 0 0-195.881 195.996c-58.034 58.092-152.004 58.093-210.048.041z"/></svg>db.jpg</a>
</div>
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db.jpg

I'm trying to figure out the best way to construct database tables to support what are, programmatically speaking, derived classes.

My base class will be "Request" 

"OriginalRequest" & "AmendedRequest" both extend "Request". 

"OriginalRequest" is a parent of "AmendedRequest" with a one-to-many relationship.

 In constructing the database tables, given that "OriginalRequest" & "AmendedRequest" are only different by one attribute and their children are virtually identical,  is it wise to build the tables as I have in the attached diagram, better to consolidate the requests and add fields to make it self-referencing to preserver the Original to Amended relationship or a different way all together?


Thanks in advance for your time & help.



What's the best way to build database tables to support derived classes &amp; similar objects?

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What's the best way to build database tables to support derived classes &amp; similar objects?

What's the best way to build database tables to support derived classes & similar objects?