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copied!<p>If I use <code>Class Table Inheritance</code> meaning:</p> <blockquote> <p>one table for Products, storing attributes common to all product types. Then one table per product type, storing attributes specific to that product type. -Bill Karwin</p> </blockquote> <p>Which I like the best of Bill Karwin's Suggestions.. I can kind of foresee one drawback, which I will try to explain how to keep from becoming a problem. </p> <p><strong>What contingency plan should I have in place when an attribute that is only common to 1 type, then becomes common to 2, then 3, etc?</strong></p> <p>For example: (this is just an example, not my real issue)</p> <p>If we sell furniture, we might sell chairs, lamps, sofas, TVs, etc. The TV type might be the only type we carry that has a power consumption. So I would put the <code>power_consumption</code> attribute on the <code>tv_type_table</code>. But then we start to carry Home theater systems which also have a <code>power_consumption</code> property. OK its just one other product so I'll add this field to the <code>stereo_type_table</code> as well since that is probably easiest at this point. But over time as we start to carry more and more electronics, we realize that <code>power_consumption</code> is broad enough that it should be in the <code>main_product_table</code>. What should I do now?</p> <p>Add the field to the <code>main_product_table</code>. Write a script to loop through the electronics and put the correct value from each <code>type_table</code> to the <code>main_product_table</code>. Then drop that column from each <code>type_table</code>.</p> <p>Now If I was always using the same <code>GetProductData</code> class to interact with the database to pull the product info; then if any changes in code now need refactoring, they should be to that Class only.</p>

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