Hide the fields for internal calculation.
An alert is window that appears in the middle of the screen overlaying a portion of the current display.
It synchronizes the terminal screen with the internal state of the form.
using On-Message or On-Error triggers.
These triggers are executes when inserting, deleting and updating operations are performed and can be used to change the default function of insert, delete or update respectively. For Eg, instead of inserting a row in a table an existing row can be updated in the same table.