Comments on: How can I subtract numeric data from two database table in Microsoft Access? http://www.childidaccess.com/microsoft-access/how-can-i-subtract-numeric-data-from-two-database-table-in-microsoft-access Sun, 12 Feb 2012 17:11:59 -0500 http://wordpress.org/?v=2.8.4 hourly 1 By: Chris G http://www.childidaccess.com/microsoft-access/how-can-i-subtract-numeric-data-from-two-database-table-in-microsoft-access/comment-page-1#comment-2384 Chris G Sun, 27 Dec 2009 17:55:59 +0000 http://www.childidaccess.com/microsoft-access/how-can-i-subtract-numeric-data-from-two-database-table-in-microsoft-access#comment-2384 It is never recommended to store dynamic information in a database. By that I mean if any of your purchaseqty in table 1 changes, or supplyqty in table 2 changed then your value stored in table 3 would be incorrect... It is better, instead of storing calculated data, to make the necessary calculations only when you need to display it to the end user. Whether that be on a form, a report, or in a data access page. Control Source for the calculated data would be: =[table 1].[purchaseqty] - [table 2].[supplyqty] OR =[table 2].[supplyqty] - [table 1].[purchaseqty] Whichever is suitable for your calculation.<br><b>References : </b><br> It is never recommended to store dynamic information in a database. By that I mean if any of your purchaseqty in table 1 changes, or supplyqty in table 2 changed then your value stored in table 3 would be incorrect…

It is better, instead of storing calculated data, to make the necessary calculations only when you need to display it to the end user. Whether that be on a form, a report, or in a data access page.

Control Source for the calculated data would be:

=[table 1].[purchaseqty] – [table 2].[supplyqty]

OR

=[table 2].[supplyqty] – [table 1].[purchaseqty]

Whichever is suitable for your calculation.
References :

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