How to subtract date values in a calculated column
The following section describes how to display the difference between two date values.
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Select a column. From the context menu, choose ColumnChoose New Computed Column. New Computed Column appears.
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In Column Label, type a name for the calculated column. For example, for a calculation that subtracts the actual shipping date from the date requested, type Shipping Delay.
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For the second argument, type a left bracket ([) and select the second date column from the list. For example, select Actual Shipping Date.
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Validate the expression and choose OK. The calculated column appears in the report, displaying the difference between the two dates.

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