So there is no need for the developer to ensure that the value is updated. With the Calculated data type, you store a formula or expression that is updated automatically when the components of the expression change. This satisfies the primary reason against storing calculations. Microsoft now provides for a new data type in Access 2010 that allows the user to store an expression that displays a value. With storage space costing around $100 per Terabyte, developers do not have to scrimp to save space. With today’s technology, storage space is not much of an issue. Second, when storage space was at a premium, it didn’t make sense to store a value that could be displayed with an expression in a control or a column in a query. Foremost is that you have to ensure that you recalculate the value when the components of the calculation change. In the past it has always made sense not to do this for a couple of reasons. One of the long held principles of data base design has been to not store calculated values.
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