UniBasic Commands Reference - Rocket Software

SUBROUTINE (Update Trigger)
Syntax
SUBROUTINE trigname(execstat, dictflag, filename, record.ID.expr, recordval)
FUNCTION trigname(dictflag, filename, record.ID.expr, recordval)
Description
Triggers enforce user-defined constraints that must be met before data can be
updated. The trigger is associated with the data file, so it verifies any access to the
data. A UniBasic trigger subroutine or function serves as an UPDATE trigger. The
SUBROUTINE or FUNCTION definition must be the first line in the UniBasic
trigger.
You must include a RETURN statement in the function:
RETURN [execstat]
Points to Remember
1-880 UniBasic Commands Reference
When you attempt to update a record, UniData calls the trigger, passing the
file name, DICT if dictionary file, record ID, and the input value before
updating the record. The subroutine returns the execution status and the new
record value.
If the update request fails, the subroutine must return an execstat value of 0.
If the request passes, the return value must be 1.
Tip: You can call a C routine from the UniBasic subroutine or function that is called
from a trigger.