"Rewrite" an application without affecting old calculations
in [Tables]
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From: Fred on 3 Dec 2009 09:04 This is a rare casse where I disagree with the other respondents. An invoice is an entity, and, roughly speaking, a one time event. At the time of the event it is derived from other data, but, after that, the result becomes an entity. Like taking a photograph of an event ....at that moment, it is "derived" from the scene, but then the photograph becomes and entity to be stored. You can't "re-derive" it later. Your math change is one example of why not. Another example is if a company changes their address and you update your db accordingly. Your invoice is a record of where it was mailed to, which is the old address. Strictly speaking, DB's such as your current one (and Northwind) do not store invoices, they merely create and export them as paper or electronic documents. Under those DB's, if you want to "store" invoices, you need to store the invoices, which are the electronic or paper documents. Ditto for transactions and orders. If the mission of your database is to store invoices within itself, then you will have to restructure it to do so which will require setting up some new tables and probably changing your definition of one or two existing tables. If this route is of interest, you could tell us that and get more help.
From: ffulmer via AccessMonster.com on 3 Dec 2009 15:05
Thank you very much for all of you to reply my question and widening my view in this topic. I will make the final decision after discussing it with the rental shop owner for whom I made this application. Once again, your help is greatly appreciated. ffulmer -- Message posted via AccessMonster.com http://www.accessmonster.com/Uwe/Forums.aspx/access-tablesdbdesign/200912/1 |