Database Reference
In-Depth Information
Figure 8-20.
Results that fail validation are highlighted and presented in the message area
Note
By default, these validations are only executed for new or changed rows. You
can change this behavior by setting the Execution Scope of the validation, located in the
Conditions section.
The Create Validation wizard also allows the creation of row-level validations on
tabular forms. These validations are run once for each row being processed by the tabu-
lar form. At this level, you could easily create a validation, similar to the one created
for page 210, that checked to see if the Closed On date was after the Created On date.
As an exercise to see how much you've learned, see if you can implement that val-
idation at the row level of the tabular form on page 230.
Computations
The APEX computation is analogous to a PL/SQL function. The intent is to act on an
item in the application by setting the value using a variety of methods. This allows in-
formation to be derived rather than just stored in the data tables. Computations can be
implemented when a page is rendered or after a page is submitted back to the server,
depending on the needs of the application. Computations can act on any item available
within an application. Items that can be set include items on the current page, items on
another page, and even application-level items.
There is also a type of computation that can be used at the application level. It's
available in an application's shared components. This type of computation has addi-
tional options for execution points including a computation point called On New In-
