ComputedField Element (ADF)
Provides a location for defining a computed notification class field.
Syntax
<NotificationClasses>
<NotificationClass>
...
<Schema>
...
<ComputedFields>
<ComputedField>
Element Characteristics
| Characteristic | Description |
|---|---|
Data type |
None. |
Default value |
None. |
Occurrence |
Required once or more per ComputedFields element. |
Updates |
Can be added and deleted when updating the application. |
Element Relationships
| Relationship | Elements |
|---|---|
Parent element |
|
Child elements |
FieldName Element for NotificationClass/Schema/ComputedFields/ComputedField (ADF) |
Remarks
Computed fields are never stored in the notifications table. Instead, they are computed immediately before the notification data is passed to the content formatter.
Computed fields allow you to make use of the calculation facilities of Microsoft SQL Server. Use of computed fields can improve the performance of your notification application, can reduce the work that you must do in the content formatter, and enables you to use the rich formatting and conversion capabilities in Transact-SQL.
Important
If you add or delete a ComputedField element, updating the application deletes and re-creates the notification class to which it corresponds. This includes dropping and re-creating the SQL Server tables used by this notification class. Make sure to back up your application database before updating the application.
Example
The following example shows a populated ComputedField element. The computed field converts the stock price into a formatted string.
<ComputedField>
<FieldName>FormattedStockPrice</FieldName>
<SqlExpression>CONVERT(NVARCHAR(10), StockPrice, 1)
</SqlExpression>
</ComputedField>
See Also
Reference
Application Definition File Reference
Other Resources
CAST and CONVERT (Transact-SQL)
Defining the Notification Schema
Updating Instances and Applications