This session, building on session 1, will look into the physical construction of trigger programs for the various types of triggers and examine in detail the parameter list passed into the trigger program from the RDBMS. This will be a discussion on general principles of trigger construction as the specific code will depend on the file and its content and the purpose trying to be achieved.
Heritage/Legacy applications have very specific problems when triggers are introduced into the database. The reason for this is typically that the heritage application code is not built to cater for the additional actions and responses introduced by the use of triggers.
This session will introduce a modified trigger construction which will allow a trigger program to be attached to a D/B file without risk to the application, or need to modify the application code, and will also assist it the evolution of the application programs to become responsive to trigger actions.