|
"The
soul is not where it lives but where it loves."
-Thomas
Fuller (1608-1661)
|
How
to use the “WHEN-VALIDATE-ITEM” trigger?
Your client has a form
that contains an item that holds a value for the “COMM-PAID-YTD”
column (Commission Paid Year To Date). They want to validate the data
in that column to be between 200 and 800 dollars. Anything else, it
must give the following error messages:
If the commission is
less than 200 then a message should be displayed as:
ERROR: Commission must be at least $200.00 or more.
If the commission is
more than 800 then a message should be:
ERROR: Year to date commission can not exceed $800.00.
You as a programmer,
asked to write a trigger to check the field item and send an error
message to a user if the data entered was violated by above rules.
Solution:
=========
Assuming that you have
a form that created by the “CUSTOMERS” table and there is an item
called “COMM_PAID_YTD.”
1- Go
to the object navigator window and expand the “COMM_PAID_YTD”
item.
2- Highlight
the “Trigger” item and click on (+) the “Create” icon.
3- Select the
“WHEN-VALIDATE-ITEM” trigger.
3- Write the following
procedure:
IF :comm_paid_ytd
< 200 THEN
-- Must be at least $200.
message('ERROR: Commission must be at least $200.00 or more.');
display_error; -- Display the message box
raise form_trigger_failure; -- to keep the cursor in the item
ELSIF :comm_paid_ytd
> 800 THEN
-- Not more than $800.
message('ERROR: Year to date commission can not exceed $800.00.');
display_error; -- Display the message box
raise form_trigger_failure;
-- to keep the cursor in the item
END IF;
4- Compile and close
the trigger.
5- Run the form, go to
the “COMM-PAID-YTD” item, and enter an invalid value such as 900
or 50.
|
