About expression columns
Using the Edit DataView Expressions form, you can create new columns
within DataViews based on expressions.
These expression columns can be created in runtime, when you interact with the DataView through the Edit DataView Expression form. This form functions similarly to the Edit Expression Binding dialog box with these changes:
- DATAVIEWPROP and DATAVIEWEXP functions are supported.
- V, P, and C functions are not supported.
- Aggregate functions are applied to DataView IDOs.
Note: The syntax or keywords are similar to component expressions with adjustments made for
DataView-specific functionality.
The expressions are stored and retrieved as part of the DataView layouts. When loading a DataView layout that contains expressions, expression columns are created and the values are calculated based on the expression.
Note: A DataView report run by Taskman creates a
temporary Mongoose report-type form and then sends
that form to the form report processor to create the report. During the creation of the
temporary report form, DataView expressions are translated into component expressions for
inclusion in the report.
This is an example of how to format an expression for use with expression columns in
DataViews:
DATAVIEWPROP( OnHand ) - DATAVIEWPROP( QtyRsvd )
This expression uses the quantity of an item that is immediately available and subtracts the quantity of that item that is reserved to calculate the quantity of the item that remains.